JP4598417B2 - Data recording / reproducing apparatus, data recording / reproducing method, program, and recording medium - Google Patents

Description

  The present invention relates to a data recording / reproducing apparatus, a data recording / reproducing method, a computer program, and a recording medium for a randomly accessible recording medium, and more particularly, to scan a magnetic head on a magnetic disk as a medium such as a hard disk. The present invention relates to a technique for a disk-type recording medium that performs data read / write operations. More specifically, the present invention relates to a technique for performing stable data recording / reproduction while shortening the access time to a desired data storage location.

JP 2000-276856 A JP 2000-278645 A

  With the development of information technology such as information processing and information communication, it has become necessary to reuse information created and edited in the past, and information storage technology has become increasingly important for this purpose. Up to now, information recording devices using various media such as magnetic tapes and magnetic disks have been developed and spread.

Among these, HDD (Hard Disk Drive) is a magnetic recording type auxiliary storage device. The HDD drive unit accommodates several magnetic media as recording media and is rotated at high speed by a motor. The medium is coated with a magnetic material such as iron oxide or cobalt / chromium by plating or forming a thin film.
Then, by scanning the magnetic head in the radial direction on the surface of the rotating medium, the magnetization corresponding to the data is generated on the medium, and writing or reading of the data can be performed.

Such hard disks are already widespread. For example, as a standard external storage device for a personal computer, for installing various software such as an operating system (OS) and applications necessary for starting the computer, and for saving created / edited files Hard disk is being used. Usually, the HDD is connected to the computer main body via a standard interface such as IDE (Integrated Drive Electronics) or SCSI (Small Computer System Interface), and its storage space is an operating system such as FAT (File Allocation Table). Managed by a file system that is a subsystem of
Recently, the capacity of HDDs has been increasing. Along with this, not only as a conventional auxiliary storage device for computers but also as a hard disk recorder for storing broadcast-received AV content, the application field has expanded, and it has begun to be used for recording various content.

Here, taking the case of being used as an auxiliary storage device for a computer as an example, the physical formatting method of the hard disk and the data read / write operation to the hard disk will be considered.
A large number of “tracks” are formed concentrically on the hard disk as sections for recording data. Then, track numbers such as 0, 1,... Are assigned from the outermost periphery to the inner periphery. The greater the number of tracks on the disk surface, the greater the storage capacity of the media.

Further, each track is divided into “sectors” which are recording units. Normal data read / write operations on the disk are performed in units of sectors. Although the sector size differs for each medium, the hard disk sector is generally set to 512 bytes in many cases. Further, in consideration of the media usage efficiency, in order to make the recording density on each track substantially uniform, the number of sectors is increased toward the outer track having a longer circumference. This is called the “Zone Bit Recording” method.
When the zone bit recording method is adopted, the recording density on each track can be made almost uniform, but the data transfer speed for each track becomes non-uniform. The data transfer rate decreases as the disk moves in the inner circumferential direction.

  Also, in the case of an HDD configured by concentrically overlapping several media, it can be considered that the same numbered track of each media is arranged in a cylindrical shape, and this is called a “cylinder”. Each cylinder is assigned the same number as the track number, and cylinder 0, cylinder 1,. The plurality of heads inserted between the media always operate as one body and move between the cylinders.

  A CHS mode can be given as a method for designating (addressing) a target sector. This is a method of accessing desired data by designating PBA (Physical Block Address) on the disk in the order of C (Cylinder), H (Head), and S (Sector).

  On the other hand, in the CHS system, there is a limit to the CHS parameters that can be specified on the computer main body side that operates as a host for the HDD, and it becomes impossible to cope with an increase in the capacity of the hard disk. For this reason, an LBA (Logical Block Address) mode is adopted. This expresses a cylinder number, a head number, and a sector number (CHS) by a logical serial number called LBA starting from 0.

  In the conventional HDD, in order to access the medium and read / write data, the magnetic head is first scanned on the medium in order to reach the track with the target sector. This is called a “seek” operation of the magnetic head. Next, in order to reach the target sector on the track, the medium rotates and waits until the target sector comes directly under the magnetic head. This is called “waiting for rotation”.

  As the capacity of the disk increases, the track density increases and the track width becomes extremely narrow. Therefore, in order to write and reproduce data accurately, positioning of the magnetic head requires high accuracy. Therefore, a servo technique is adopted in which the position of the magnetic head is always aligned with the center of the track. It is possible to check whether or not the magnetic head is at the center of the track by writing signals called “servo patterns” on each track at regular intervals and reading them with the magnetic head. The servo pattern is written with high accuracy in the manufacturing process of the HDD. For example, a signal for positioning the head, a cylinder number, a head number, and a servo number are written in the servo area.

Many conventional HDDs have an interface such as IDE or SCSI for connection to a computer. Then, the disk drive control from the computer main body has a basic operation of designating the LBA indicating the head sector and the number of sectors to be accessed using a command set defined by the interface.
In this case, on the HDD side, access can be made while creating from the designated head sector and creating a sequence for prefetching by predicting the sector to be accessed thereafter.
This pre-read operation is based on the premise that sectors having continuous addresses are allocated to a series of data. Normally, sectors having consecutive addresses exist in consecutive head numbers or track numbers.
When large data is continuously written on the medium, the prefetching operation at the time of reading works effectively.

  However, when fragmentation of the storage area proceeds and large data is fragmented into small pieces and distributed in multiple locations, the read-ahead at the time of reading points to other data, so it works effectively. I can't. It can be said that such a phenomenon occurs because the HDD does not grasp the file structure handled by the host (computer main body or the like) side that requests data read / write.

  In addition, when the prediction is lost due to a new access request from the host side, the disk drive seeks to the track including the sector where the requested data exists, and when the tracking is completed, the target sector is not accessed. Wait for it to be possible. Here, seek time and rotation waiting time occur.

  Prefetched data is stored as long as the capacity of the data buffer allows. If the prediction is lost continuously or sporadically, the unused old data in the data buffer is discarded in order. Further, seek activation cannot be performed during this prefetching.

As described above, it can be said that seek time and rotation waiting time, time loss due to seek start delay due to invalid prefetching, and data loss due to invalid prefetching have occurred.
In a normal disk drive, in order to shorten the seek time and the rotation waiting time, the rotation speed of the disk is increased. This is because there is no regularity in the amount of data and the data structure handled on the host side such as a computer, and thus it is difficult to improve by the access method. However, the method of increasing the number of revolutions of the disk is disadvantageous in terms of power consumption and storage capacity, and causes a problem.

In many conventional external storage systems such as HDDs, error correction is performed in units of one sector (one sector is usually composed of 512 bytes). As a result, error correction can be performed for random errors occurring in each sector. Error correction cannot be performed for random errors or burst errors that exceed the correctable range. In view of this, the read error has been kept below a certain level by performing a retry operation.
However, such a retry operation needs to be read again after waiting for one rotation. This further causes a delay in data read time.
For example, in a system that handles AV content, there is a situation where high transfer speed is required, such as HD (high definition image quality) playback or special playback, and even if an uncorrectable read error occurs in a sector, time Sometimes it is not possible to retry. In such a case, at present, the process cannot be advanced without error correction, and as a result, the reproduction quality is deteriorated.

For example, the above-mentioned Patent Document 2 has information indicating the importance level of the data block to be recorded, and based on this information, retry is performed for the important data block, and no retry is performed otherwise. A technique for switching is disclosed.
Further, the above-mentioned Patent Document 1 has information indicating the importance of the data block to be recorded, and based on this information, the error correction capability is increased for the important data block, and other than the normal correction capability. A technique for performing such switching is disclosed.
These techniques function appropriately to some extent, particularly in systems that handle AV contents, but more effective techniques are required for avoiding retries and correcting errors.

Furthermore, as the HDD density increases, the disk format is further subdivided in order to improve efficiency. For example, in addition to optimizing the recording / reproducing frequency and rotational speed on the disc and increasing the number of zones, for example, when there are a plurality of discs or a plurality of recording / reproducing heads in the HDD, each disc surface In the above, it is conceivable that even at the same zone position, the recording density is made variable according to the characteristics of the recording / reproducing head given to each disk surface, and the clock and the track interval are switched when the head is switched.
Thus, by using a finer format structure, the recording density of the HDD is improved and the yield is expected to be improved.
Along with this, with regard to error correction capability, it is desired to improve efficiency and improve quality over the entire circumference of the disk.

In the HDD, addresses are already allocated so as not to access a sector unit portion on the disk which is not appropriate at the time of shipment. This state is called slip, and there are a case where a specific number of sectors are slipped on a predetermined track and a case where a certain number of sectors are slipped. When several tens of sectors are slipped on the track, the effective data sector area per track is greatly reduced.
The above-mentioned demand for higher density is required to cope with such circumstances, and the disk format includes, for example, information on slips that are different for each HDD, and more efficient error correction blocks. A configuration is desired.

The present invention has been made in view of the above-described problems, and realizes the following objects as a data recording / reproducing apparatus, a data recording / reproducing method, a computer program, and a recording medium.
That is, the access time to a desired data storage location is shortened.
In addition, stable data reproduction is performed without reducing the transfer rate.
In addition, by making it possible to correct errors over a wider range of random errors and burst errors, it is possible to avoid a retry operation, reduce a decrease in transfer speed, and perform stable data reproduction.
In addition, an error correction method that can cope with subdivision of the format configuration is realized.

The data recording / reproducing apparatus of the present invention is a data recording / reproducing apparatus for a disk recording medium in which concentric or spiral tracks are formed and each track is divided into a plurality of sectors. Means for seeking data, data access means for accessing on the seeked track, and error correction means for generating an error correction code for error correction of the data and correcting the error of the data based on the error correction code And control information generating means for generating control information of an error correction block corresponding to access by the data access means to the disk recording medium. The control information generating means generates the control information according to the number of sectors in a unit of predetermined processing data, which is adapted to an image or sound in a range accessed by the data access means, and the error correction means A first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of the first error correction code units are set. An error correction block comprising an error correction code unit and the second error correction code unit added thereto is formed, and the number of sectors in the second error correction code unit is set by the control information generating means This is performed based on the control information generated by.
In particular, the number of sectors in the range accessed by the data access means is the number of sectors in one track accessed by the data access means.
More specifically, the control information generating means determines the number of sectors in the second error correction code unit and the contents of interleaving (the number of interleave divisions and each interleaving) according to the number of sectors in the range accessed by the data access means. The control information indicating the second error correction code sector number) is generated.
The error correction means sets the number of sectors in the second error correction code unit according to the control information, and generates an error correction block having an interleave structure according to an instruction of the interleave contents.

The control information generating means comprises a data table storing the number of sectors in the range accessed by the data access means and the number of sectors or the number of interleave divisions of the second error correction code unit corresponding to the number of sectors, and the data access The control information indicating the number of sectors in the second error correction code unit or the number of interleave divisions is generated by referring to the data table in accordance with the number of sectors in the range accessed by the means.
Alternatively, the control information generation means generates the control information indicating the number of sectors or the number of interleave divisions of the second error correction code unit by performing arithmetic processing on the number of sectors in the range accessed by the data access means.
In these cases, the number of sectors in the second error correction code unit is a positive integer derived from a numerical value calculated by a predetermined redundancy ratio according to the number of sectors in the range accessed by the data access means. And

In the data recording / reproducing method of the present invention, concentric or spiral tracks are formed, and each track is divided into a plurality of sectors. A seek step, a data access step for performing access on the seek track, an error correction step for generating an error correction code for error correction of the data and correcting the error of the data based on the error correction code, A control information generating step for generating control information of an error correction block corresponding to the access by the data access step to the disk recording medium. The control information generating means generates the control information according to the number of sectors in a unit of predetermined processing data, which is adapted to the image and sound in the range accessed by the data access means, and in the error correction step, A first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of the first error correction code units are set. An error correction block comprising an error correction code unit and the second error correction code unit added thereto is formed, and the setting of the number of sectors in the second error correction code unit is performed in the control information generation step This is performed based on the control information generated by.
In the control information generation step, control information indicating the number of sectors and the number of interleave divisions in the second error correction code unit is generated.
The number of sectors in the range accessed in the data access step is the number of sectors in one track accessed in the data access step.

  In the program of the present invention, concentric or spiral tracks are formed, and each of the tracks is computer-readable for executing a data recording / reproducing process on a disk recording medium divided into a plurality of sectors on a computer system. It is a program described in a format, and is a program for executing the steps of the data recording / reproducing method.

  The recording medium of the present invention is a recording medium characterized in that data having the following error correction block configuration is recorded on tracks formed concentrically or spirally. In the error correction block, a first error correction code unit is set for a predetermined data amount unit, and second error correction code units for a plurality of first error correction code units are set. The first error correction code unit and the second error correction code unit added thereto. In the error correction block, the second error correction code unit is set based on the number of sectors in a range in which data write / read access is performed.

With the above-described present invention, the above-described intended object is realized.
That is, the random error in the sector can be corrected by using the first error correction code (C1) unit, and the intra-sector error correction range can be increased by using the second error correction code (C2) unit. It is possible to correct errors that exceed or burst errors that span sectors. In other words, by setting the error correction block configuration to C1 + C2, even when retrying cannot be performed to maintain the data transfer rate higher than desired, error correction is further performed at C2 when error correction becomes impossible at C1. Therefore, a more stable system can be provided. In this way, it is possible to perform error correction even for random errors and burst errors in a wider range, and by avoiding the retry operation, stable data reproduction can be performed without reducing the transfer speed. .
Furthermore, the error correction block configuration, particularly the number of C2 sectors, is set according to the number of sectors in the access range (for example, one track), thereby including the influence of the recording / reproducing head, recording surface, zone, or slip. It is possible to deal with a segmented sector format. In other words, it is possible to avoid the occurrence of variations in error correction capability, to realize efficient error correction, and to make it suitable in terms of transfer rate.

Further, the data access means starts access from the head sector that has become accessible on the track sought by the seek means, and performs access for one track. For example, an access for one track is performed from a sector in which the magnetic head is on-track. In other words, by using one track as an access unit, it is possible to reliably determine the seek activation timing without the indefinite process of prefetching.
In particular, in this case, the data access means allocates relative position addresses in order from the sector that started access on the track to each sector at the time of write access, and data read from each sector on the track at the time of read access. Can be accessed from any sector of the track by reproducing the written data according to the relative position address and reproducing the written data. Can be eliminated. As a result, the number of seeks is minimized, and the access time is shortened.
Further, a request source for writing or reading (for example, a host device such as a computer connected to the HDD) does not need to be aware of the sector address on the disk. Further, by using a relative position address that requires a short data size, the storage area can be effectively used .

According to the present invention, it is possible to provide an excellent data recording / reproducing apparatus, data recording / reproducing method, program, and recording medium capable of performing efficient and stable data reproduction with redundancy by error correction codes. it can.
That is, the random error in the sector can be corrected by using the first error correction code (C1) unit, and the error correction range in the sector can be obtained by using the second error correction code (C2) unit. It is possible to correct errors that exceed, or burst errors that span sectors. As a result, even in a situation where a retry cannot be performed in order to keep the data transfer rate higher than desired, an error can be corrected appropriately and a more stable system can be provided. In this way, it is possible to perform error correction even for random errors and burst errors in a wider range, and by avoiding the retry operation, stable data reproduction can be performed without reducing the transfer speed. .
Further, as the error correction block configuration, the number of sectors in the second error correction code (C2) unit and the interleave structure (for example, the number of interleave divisions) are set according to the number of sectors in the range to be accessed. The error correction block will be optimized according to the status of the actual access range such as recording surface, zone, slip condition, etc. In other words, avoiding variations in error correction capability or efficient error correction And an efficient disk format can be realized. In addition, an efficient error correction block is also preferable in terms of the transfer rate because it is avoided that redundancy becomes unnecessarily high. As a result, a more stable system can be provided.

In order to generate control information indicating the number of sectors in the second error correction code unit or the interleave contents, the number of sectors and the number of sectors in the second error correction code unit corresponding to the number of sectors or the number of interleave divisions are set. If a stored data table is provided, the number of sectors in the second error correction code unit or the number of interleave divisions can be easily referred to the data table according to the number of sectors in the range accessed by the data access means. Control information for instructing can be generated.
Alternatively, the control information generating means generates the control information indicating the number of sectors or the number of interleave divisions of the second error correction code unit by arithmetic processing on the number of sectors in the range accessed by the data access means. In this case, the data table need not be provided.
The number of sectors in the second error correction code unit indicated by the control information is a positive value derived from a numerical value calculated by a predetermined redundancy ratio according to the number of sectors in the range accessed by the data access means. It is appropriate to use an integer of.

Furthermore, according to the present invention, one track can be set as an access unit by starting the access from the first sector that can be accessed on the sought track. It is possible to realize data access control that does not generate a problem. That is, the data access time can be shortened.
In particular, in the case of this access method, the configuration of the error correction block only needs to be set according to the number of sectors in one track, and the above effect can be obtained.

Hereinafter, embodiments of the present invention will be described in the following order with reference to the drawings.
1. 1. Configuration of hard disk device 2. Access operation ECC configuration4. 4. ECC block setting according to the number of sectors Application examples

1. Hard disk unit configuration

FIG. 1 schematically shows an overall configuration of an HDD (Hard Disk Device) 10 according to an embodiment of the present invention.
As shown in the figure, the HDD 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) / RAM (Random Access Memory) 12, a disk controller 13, a buffer RAM 14, a data read / write control unit 15, and the like. , A servo controller 16 and a magnetic disk 21.

The magnetic disk 21 is composed of one or a plurality of sheets, and the recording surface is single-sided or double-sided (front and back of the disk). A head is disposed on the recording surface. FIG. 1 shows a state in which two magnetic disks 21a and 21b are arranged and two recording / reproducing heads (magnetic heads) 22a and 22b are provided correspondingly.
In other words, several magnetic disks (platters) can be concentrically overlapped in the drive unit. At that time, the same track number of each magnetic disk is arranged in a cylindrical shape (cylinder), and the same cylinder as the track number. It is specified by number.
As shown in FIG. 1, one recording / reproducing head 22 is arranged for one magnetic disk 21 when one side of the magnetic disk 21 is a recording surface.
When both surfaces are recording surfaces, two recording / reproducing heads 22 are arranged for one magnetic disk 21.

The CPU 11 executes control codes stored in the ROM / RAM 12 and controls the operation in the HDD 10 in an integrated manner.
The disk controller 13 receives a command from a host (not shown) connected via the interface 17. The CPU 11 performs this command processing, and the disk controller 13 instructs a hardware operation to the data read / write control unit 15 and the servo control unit 16 according to the command processing result.
Write data received from the host via the interface 17 and data read from the magnetic disk 21 and passed to the host are temporarily stored in the buffer RAM 14.

  The data read / write control unit 15 performs a code modulation process to create a data pattern to be actually recorded, and writes data to the magnetic disk 21 via the preamplifier 25. Conversely, the read data is taken in from the magnetic disk 21 via the preamplifier 25 and the data is demodulated.

  The servo control unit 16 synchronously drives a voice coil motor (VCM) 23 that moves an arm on which the magnetic head 22 is mounted and a spindle motor (SPM) 24 that rotates the magnetic disk 21, so that the magnetic head 22 becomes a magnetic disk. 21 is controlled to reach a predetermined range on the target track. Furthermore, control is performed to seek the head position to a predetermined position from the servo pattern on the disk.

A large number of tracks, which are sections for recording data, are formed concentrically on the magnetic disk 21. For example, the track numbers are 0, 1, 2,... From the outermost periphery of the disk 21 toward the inner periphery. Allocated. Each track is further divided into sectors, and this sector unit is the minimum unit in which data read / write operations can be performed.
The amount of data in the sector is fixed at 512 bytes, for example.
In addition to data, header information, error correction code, and the like are added to the actually recorded sector.

FIG. 1 shows an ECC control information generating unit 26 particularly straddling the CPU 11 and the ROM / RAM 12.
The ECC control information generation unit 26 is a part that generates control information that indicates the sector structure and interleave structure of the second error correction code C2.
The ECC control information generation unit 26 uses, for example, the ROM / RAM 12 as a location for storing a table used for generating control information, and the CPU 11 performs the control thereof to realize the function.
The format to be recorded / reproduced is determined by the control signal from the ECC control information generator 26. The format is, for example, a format in which the number of sectors in a track unit is integrated into an ECC block, and there is a C2 sector for performing error correction between sectors. The number of C2 sectors is determined based on the sector number information for each track on the disk 21 given in advance.

The information on the number of sectors for each track of the magnetic disk 21 may be stored in the ROM / RAM 12. Alternatively, for example, a predetermined area on the magnetic disk 21 may be determined and stored there. good.
The format of the number-of-sectors information for each track may store, for example, the number of sectors in each track, and in the case of an LBA system, the head LBA address of each track. After all, any format can be used as long as the number of sectors per track is known.

Further, information relating the number of sectors for each track and the number of parity actually determined (the number of C2 sectors), for example, the above table, is stored in the RAM / ROM 12 and, for example, a predetermined area on the magnetic disk 21 May be stored.
Further, the sector number information for each track and the information relating the actually determined parity number (C2 sector number) have a table format, and a calculation formula that outputs the determined parity number with respect to the input sector number You may have in. The table and calculation formula will be described later.
In addition, when the information for generating the control information, that is, the table or the calculation formula is stored in, for example, the magnetic disk 21 instead of the ROM / RAM 12 attached to the CPU 11, the information is read from the magnetic disk 21 at the time of startup. And may be stored in the buffer RAM 14.

In the magnetic disk 21, a ZBR (Zone Bit Recording) method is employed in which the number of sectors per round is such that the number of sectors is increased toward the outer track having a longer circumference. That is, the number of sectors per track over the entire circumference of the magnetic disk 21 is not uniform, and the magnetic disk 21 is divided into a plurality of zones in the radial direction, and is set to have the same number of sectors in each zone.
FIG. 2 shows an example of the ZBR method.
In the example shown in the figure, the disk is divided into three zones, and zones 0, 1, 2 and zone numbers are given in order from the outermost periphery. Further, each zone includes a plurality of tracks.
In FIG. 2, each zone is divided by sectors. In this case (as a schematic example only), zone 0 is composed of 32 sectors. Similarly, zone 1 is 16 sectors and zone 2 is 8 sectors. Each is composed. When switching zones, the number of sectors, the spindle motor 24 rotation speed is kept constant, the recording / reproducing clock is made variable, etc., the linear recording density is kept within a predetermined range, and the storage capacity per disk is increased. To be determined.

  FIG. 3 shows the internal configuration of the disk controller 13 of FIG. 1 in more detail. As shown in the drawing, the disk controller 13 includes a CPU interface 31, a host controller 32, a buffer controller 33, a servo controller 34, a disk formatter 35, and an ECC controller 36. In the figure, an arrow that causes data movement is indicated by a double line.

The CPU interface 31 is an interface between the CPU 11 and the RAM / ROM 12, and notifies the CPU 11 of a command from the host, receives a command processing result from the CPU 11, and the like.
The host controller 32 communicates with a host connected via the interface 17.
The buffer controller 33 controls the exchange of data between the buffer RAM 14 and each unit in the disk controller 13.
The servo controller 34 reads the servo information from the servo pattern on the magnetic disk 21 by controlling the operations of the VCM (voice coil motor) 23 and the SPM (spindle motor) 24, and passes this information to the servo controller 15.
The disk formatter 35 performs control for writing data on the buffer RAM 14 to the magnetic disk 21 or reading data from the magnetic disk 21.
The ECC controller 36 generates and adds an ECC code from the data stored in the buffer RAM 14 at the time of writing, and performs error correction at the time of reading.

The disk controller 13 shown in FIG. 3 receives formatter control information and ECC switching control information corresponding to the number of sectors from the CPU 11 (and the ECC control information generating unit 26 formed by the CPU 11 and the ROM / RAM 12). .
That is, the disk controller 13 receives the control information of the number of C2 sectors and interleaved content by the ECC control information generation unit 26 through the CPU interface 31. Then, formatter control information based on the determined number of C2 sectors is sent to the disk formatter 35, and information on the determined number of C2 sectors, that is, necessary information, is sent to the ECC controller 36, respectively.

  By the way, as an access method of this example, an access may be performed based on a so-called LBA (Logical Block Address), or, as will be described later, an access using a relative address in units of tracks may be performed.

In the case of accessing by LBA, the formatter control information is format information for accessing the sector specified by LBA after being accessible on the sought track. This information is sent to the disk formatter 35 via the CPU interface 31, where a data formatter is generated.
Further, the ECC switching control information by the ECC control information generating unit 26 is information for setting the ECC block configuration having the first error correction code C1 and the second error correction code C2, and this information is The data is sent to the ECC controller 36 via the CPU interface 31, where an ECC block configuration is set, and the buffer RAM 14 is accessed to perform a predetermined ECC process.
For example, the ECC block configuration is set according to the number of sectors of the track to be accessed, that is, according to the status of the track for recording / reproduction (recording surface, zone for recording / reproduction, head for performing recording / reproduction, slip status, etc.) This means that the ECC block configuration is switched.

When accessing using a relative address in units of tracks, the formatter control information starts accessing from the first sector after it becomes accessible on the seek track, and accesses for one track. The format information is sent to the disk formatter 35 via the CPU interface 31, where a data formatter is generated.
The control information for ECC switching by the ECC control information generation unit 26 is information for setting an ECC block configuration that is completed in units of tracks. This information is sent to the ECC controller 36 via the CPU interface 31. Here, the ECC block configuration is set, and the buffer RAM 14 is accessed to perform a predetermined ECC process.

Since the buffer RAM is also related, the ECC switching control information may be used by the buffer controller 33.
In addition, when storing information for generating the control information, that is, a table or a calculation formula, for example, on the magnetic disk 21, the information is read from the magnetic disk 21 and stored in the buffer RAM 14 at startup. Also good. In that case, ECC switching control information corresponding to the number of sectors may be generated in the disk controller and supplied to the ECC controller 36 or the like. That is, the function as the ECC control information generation unit 26 may be realized in the disk controller 13.

By the way, the control information by the ECC control information generation unit 26 includes the following, for example.
(1) Information specific to a track having a determined C2 sector number based on the number of sectors per track.
(2) Specific information of the unit having a determined C2 sector number based on the number of sectors of the unit that is a predetermined unit.
Here, the unit is one large unit as a unit of predetermined processing data adapted to, for example, a certain image or sound. This unit is given at physical positions in the magnetic disk 21. If the LBA method is used, the unit is a continuous LBA number. If the relative address access method is used, this unit is a range of a continuous track. In addition, the unit is selected as an area in which sector information does not vary greatly, such as zone switching.

  In other words, in this example, the ECC control information generation unit 26 generates control information including the number of C2 sectors according to the number of sectors in the range to be accessed. Here, the number of sectors in the range to be accessed is one track to be accessed. The number of sectors may be considered, or the number of sectors of one unit to be accessed may be considered.

The HDD 10 according to the present embodiment is configured as described above. In this configuration, as described below, data access control that does not cause rotation waiting is performed, and access time is shortened and data transfer speed is reduced. Realize a fast system. In addition, by making it possible to correct errors over a wide range of random errors and burst errors, a retry operation can be avoided, a decrease in transfer speed can be reduced, and stable data reproduction can be performed. In addition, optimum ECC processing is realized in consideration of segmentation of the format configuration, recording surface and head characteristics, slip conditions, and the like.

2. Access behavior

As described above, as an access method, an access method based on LBA and an access method using relative addresses in units of tracks are conceivable. Since the access method based on the LBA is an access method that is usually adopted in many HDDs, an access method using relative addresses in units of tracks will be described here, although detailed description is avoided.

In the case of this access method, in the HDD (hard disk device) 10, one track is accessed from the sector on which the magnetic head 22 is on-track. Sector numbers on the same track are not fixed and can be given by relative positions.
As a result, access can be started from any sector on one track. That is, by using one track as an access unit, it is possible to reliably determine the timing of seek activation without the need to perform processing consisting of an uncertain element such as prefetching. In addition, it is not necessary to wait for rotation by accessing from any sector of one track. As a result, the number of seeks can be minimized and the access time can be shortened.

When writing to a predetermined track, a relative position starting from the sector where access is started is given to the sector.
Further, when reading is performed, reading is performed from the sector where access is started, and the data is developed on the buffer RAM 14 based on the relative position sector number. Therefore, reading may be started from any sector.

An example of the sector format used in the track of the magnetic disk 21 to enable such an operation is schematically shown in FIG.
As shown in FIG. 4A, the sector is composed of relative position data representing the relative position of the sector on the track, a data body, and an ECC for performing error correction on the entire sector area. These are the error correction range and recording range.
By including the relative position data as a header in the error correction range, for example, even if a random error occurs in a sector, the relative position data can be recovered by error correction, thereby realizing a smooth disk access operation. be able to.
In general, a sector has an ID field for recording the address of the sector. However, since a relative position is recorded instead of an absolute position, the size of the ID field can be reduced. Accordingly, the field size that can be used for the data body in the sector increases, and the storage area is effectively used.

When writing to a track, the sector is given a relative position starting from the sector from which access was started, ECC data is generated based on the relative position and the original recording data, and the relative position field, data field, and Record in the ECC field. Since writing starts from the sector where access is started, there is no need to wait for rotation.
Further, when reading is performed, reading is performed from the sector where access is started on the track, and the storage position on the buffer RAM 14 is determined based on the sector position obtained by the relative position field. Therefore, even if data reading is started from an arbitrary sector, the data stored on the track is restored in the original order by rearranging the data on the buffer RAM 14 based on the relative position. Further, since reading is started from the sector where access is started, there is no need to wait for rotation.

FIG. 4B schematically shows another example of the sector format used in the track of the magnetic disk 21 in the HDD 10 according to the present embodiment.
Also in this case, as described above, the sector is composed of relative position data representing the relative position of the sector on the track, a data body, and ECC for performing error correction on the entire sector area. However, the entire error correction range is used, but unlike the example shown in FIG. 4A, the relative position field is not included in the recording range. Therefore, as the relative position field disappears, the field size usable for the data body in the sector becomes larger than in the above-described example, and the storage area is effectively used.

In this case, when writing to the track, a relative position starting from the sector where access was started is given to the sector, ECC data is generated based on the relative position and the original recording data, and only the recording data and ECC data are recorded on the sector. To record. Since writing starts from the sector where access is started, there is no need to wait for rotation.
When reading is performed, reading is performed from the sector where access is started, and error correction is performed using ECC, thereby regenerating a relative position that was not written in the sector. Based on this relative position, the storage position on the buffer RAM 14 is determined. Therefore, even if data reading is started from an arbitrary sector, the data stored on the track is restored in the buffer RAM 14 in the original order. Further, since reading is started from the sector where access is started, there is no need to wait for rotation.

An example of communication with the host at the time of data recording / reproducing according to the above sector format will be described.
An example of communication when the HDD 10 of this example performs data writing by a command from a host connected via the interface 17 is as follows.
First, the host issues a data write command to the HDD 10. In response to this, the HDD 10 responds with an address area having the minimum seek time from the current access sequence.
When the host receives a response from the HDD 10, the host transfers the data content of the designated address area size (number of bytes, number of sectors, etc.). The HDD 10 writes the received data content in units of tracks.

Here, as described above, when relative position information is allocated to each sector with reference to the access start position on the track at the time of writing, when the write request is made, on the host side, specific information such as the cylinder number, head number, sector number, etc. There is no need to be particularly aware of a particular writing place, and there is no need to indicate these.
Further, the address area notified from the HDD 10 side to the host may be a simple one such as a content number for identifying content requested to be written by the host.
On the HDD 10 side, a conversion table of each content number and a physical recording location on the disk 21 is prepared.
Since the disk access is performed in units of tracks, the conversion table with the content number is as shown in FIG. 5, for example. That is, track numbers and head numbers are registered corresponding to the content numbers.

Note that the sector number of the CHS method is not included in the conversion table. As described above, in the configuration in which the relative position information is allocated to each sector based on the access head sector on the track at the time of writing, the data is based on the relative position information of each sector regardless of the access head sector on the track at the time of reading. Relocation is possible. For this reason, it is not necessary to specify the access start sector in the conversion table.
This conversion table is written in the buffer RAM 14. The conversion table is written by software executed by the disk controller 13 or the CPU 11 when write data is received from the host.

A communication example when the HDD 10 of this example reads data by a command from a host connected via the interface 17 is as follows.
The host issues a data read command to the HDD 10. The target content number is specified in the read command.
On the other hand, the HDD 10 specifies the target track from the conversion table of FIG. 5 based on the content number, and performs the seek operation of the magnetic head 22. Then, the data on the disk 21 is transferred in accordance with the sequence of the address area responded at the time of data writing.
At the time of this data read request, the host side only specifies a desired content number, and does not need to be aware of a specific write location (PBA) such as a cylinder number, a head number, or a sector number.

As described above, the HDD 10 accesses one track from the sector on which the magnetic head 22 is on-track. By using one track as an access unit, it is possible to reliably determine the timing of seek activation without the indefinite process of prefetching. In addition, since access can be performed from any sector of the track, read / write is performed from an arbitrary head position immediately after seek, thereby eliminating the waiting for rotation. As a result, the number of seeks is minimized, and the access time is shortened.
Such a disk access operation is realized by the disk controller 13 instructing a hardware operation to the data read / write control unit 15 and the servo control unit 16 according to the command processing result by the CPU 11.

3. ECC configuration

As described above, when the HDD 10 accesses in units of one track, it is appropriate that an ECC block with one track as a basic unit is formed on the magnetic disk 21.
When an access method based on LBA is adopted, an ECC block having one track as a basic unit is not necessarily formed, but of course, one track may be used as a basic unit.
Here, an example of an ECC block based on one track will be described.

FIG. 6 shows an example of the ECC configuration with one track as a basic unit.
In the example of FIG. 6A, the magnetic disk 21 is divided into zones, and an example of the ECC block configuration in the zone n is shown. That is, as in a predetermined track TK indicated by a broken line in the zone n, one round of each track is set as a structural unit of the ECC block.
The ECC block includes C1 that performs intra-sector correction and C2 that performs inter-sector correction.
An error correction unit (ECC block constituent unit) composed of C1 + C2 has one track as a basic unit, and no two or more ECC block constituent units exist in each track.

FIG. 6B shows another example of the ECC block. Also in this case, the magnetic disk 21 is divided into zones, and an example of an ECC block is shown in the zone m. In this example, three tracks in the zone m become ECC block constituent units. This example uses an integral multiple of one track as a structural unit, and is not limited to three tracks of course.
Also in such an example, the ECC block includes C1 that performs intra-sector correction and C2 that performs inter-sector correction. An error correction unit (ECC block constituent unit) composed of C1 + C2 has one track as a basic unit, and no two or more ECC block constituent units exist in each track.

FIG. 7 shows an example of the ECC block structure of the magnetic disk 21 adopting the ECC block configuration shown in FIG.
Here, it is assumed that a Reed-Solomon code having a symbol length of 8 is used as the ECC correction code.
The effective number of sectors for one track in a zone of the magnetic disk 21 is 800 sectors. For example, one sector includes 4 bytes of CRC (cross check code) and a total of 48 bytes of C1 to 512 bytes of data, and is composed of 4 interleaves.

In the example of the ECC block configuration of FIG. 7, 752 sectors from sectors 0 to 751 are given as data areas, and 48 sectors from sectors 752 to 799 are given as C2 areas. C2 is composed of, for example, 4 interleaves of 12 sectors each.
In such a configuration, one ECC block has a total of 800 sectors, which is equivalent to one round in this zone, and a track unit can be realized.

Consider the error correction capability in this example.
By using C1 for a random error, it is possible to correct up to 24 bytes per sector (up to 48 bytes if byte loss information is obtained).
Furthermore, for burst errors, error correction with a length of up to 24 sectors per track (up to 48 sectors using the CRC result) is possible by using C2.

Here, the circumstances of adopting the error correction block as described above will be described.
In many conventional HDD systems, error correction is performed only in units of one sector including 512-byte data and information bits.
Therefore, error correction can be performed for random errors occurring in each sector, but for random errors that exceed the correctable range, or burst errors, that is, errors that continue long beyond the sector, Error correction could not be performed.

In such a case, for example, by performing a retry operation, it is possible to make the read error below a certain level and perform error correction. However, the retry operation basically corresponds to an increase in the extra access time for one turn per time.
Here, even if the access time is shortened by the track unit access as described above, if a retry operation occurs, the access time eventually increases, resulting in a delay in data read time.
For example, when handling AV content such as HD (high-definition image quality) playback or special playback, when a high transfer speed is required, even if an uncorrectable read error occurs, there is no time to perform a retry operation in time. There is. In such a case, at present, the processing is proceeding without correcting the reading error. As a result, the reproduction quality is deteriorated.

Therefore, the ECC configuration is configured as described above to realize stable data reproduction and reduce the number of cases where error correction that causes a retry occurrence cannot be performed.
That is, in addition to the conventional C1 correction, which is an error correction in units of one sector, a C2 correction capable of correcting between sectors is added. The error correction unit (ECC block) composed of C1 + C2 is completed by, for example, a track.

When an ECC block unit composed of C1 + C2 is completed in one round of a track, one track can be used as an access unit, and data access control without causing rotation waiting can be realized. That is, the access time to a desired data storage location can be shortened. Also, if there are no more than two ECC blocks on the same track, data access control that does not cause rotation waiting can be performed even when the ECC configuration is a unit of a plurality of tracks. Can be realized.

4). ECC block setting according to the number of sectors

For example, assuming that an ECC block is formed in units of one track, the ECC block in the case where one track has 800 sectors is shown in FIG.
However, all tracks on the magnetic disk 21 are not 800 sectors. Actually, in addition to the number of sectors per track differing depending on the zone, the disk format may be subdivided for higher density and higher efficiency. For example, the recording density may be variable for each disk surface, each recording / reproducing head, or the like, or the zone may be divided in more detail on one recording surface, or the zone configuration may be different for each disk surface. Furthermore, there is a track in which a certain sector section is deleted (invalidated) as a slip.
In other words, the number of sectors in each track of the magnetic disk 21 is diversified in consideration of the influence of format fragmentation and slipping according to the demand for higher density and the like.
In this example, even in such a situation, in order to realize an efficient error correction block, the ECC block configuration is set according to the number of sectors per track.
That is, the ECC control information generation unit 26 shown in FIG. 1 generates control information indicating the number of C2 sectors and the number of interleave divisions as described below based on the information on the number of sectors of the track to be accessed, as described below. As described above, it is supplied to the ECC controller 36 and the like to form an efficient ECC block.

  Here, the ECC block setting based on the number of sectors per track is described as an example, but the concept is the same in the case of the ECC block setting based on the number of sectors per unit as described above.

For example, as described above, the ECC control information generation unit 26 generates control information such as the number of C2 sectors by referring to the table from the number of sectors of the track to be accessed or by a predetermined calculation process based on the number of sectors of the track to be accessed. .
First, an example of a table when referring to the table is shown in FIG.
The table of FIG. 8 is a table showing the number of C2 sectors and the number of interleave divisions for 1 to 1020 sectors as one sector per track. As described above, such a table is stored in the ROM / RAM 12, for example.

In this case, the redundancy is set to a predetermined numerical value (%) with respect to the number of sectors per track, and the number of C2 sectors corresponding thereto is given. As an example, the redundancy is 6%.
The number of C2 sectors is an integer obtained by multiplying the number of sectors per track by the redundancy and rounding off the first decimal place.
For example, as the number of sectors per track, 1, 2, 3,.
1 × 0.06 = 0.06
2 × 0.06 = 0.12
3 × 0.06 = 0.18
4 × 0.06 = 0.24
5 × 0.06 = 0.30
6 × 0.06 = 0.36
7 × 0.06 = 0.42
8 × 0.06 = 0.48
9 × 0.06 = 0.54
10 × 0.06 = 0.60
11 × 0.06 = 0.66
(Hereinafter abbreviated)
However, in this case, since the multiplication result becomes “0” by rounding up to 1 to 8 sectors, the number of C2 sectors = 0 in the case of 1 to 8 sectors as shown in FIG. To do.
Similarly, the number of sectors 9 to 24 is shown as C2 number of sectors = 1, the number of sectors 25 to 41 is shown as C2 number of sectors = 2, and so on.

Interleaving is maximized at 255 sectors, and the number of interleavings is increased when this is exceeded.
That is, as shown in the figure, when the number of sectors is 1 to 255, the number of interleave divisions = 1, when the number of sectors is 256 to 510, the number of interleaving divisions = 2, when the number of sectors is 511 to 765, the number of interleaving divisions is 3, and the number of sectors. In the case of 766 to 1020, the number of interleave divisions was set to 4.

When the Reed-Solomon code method is composed of n bits, a value as a division criterion in the interleave configuration can be given as follows. That is,
2 ⁿ -1
For example, in the case of 8 bits, 2 ⁸ -1 = 256-1 = 255. Therefore, 255 sectors are maximized as described above, and the number of interleave divisions is increased by 1 each time 255 is increased.

Also, the number of C2 sectors per interleave (C2 / Intv) when interleaving is given. For example, when the number of interleave divisions = 2, it is the number of C2 sectors given to each interleave.
In the case of FIG. 8, the number of C2 sectors given to each interleave is the same.
In the figure, the number of C2 sectors per interleave (C2 / Intv) is expressed as x · x when the number of interleave divisions = 2, x · x · x when the number of interleave divisions = 3, and number of interleave divisions = 4. In the case of x, x, x, x, this indicates that the number of C2 sectors given to each interleave is “x”.

For the number of sectors 1 to 255, since the number of interleave divisions = 1, the number of C2 sectors per interleave (C2 / Intv) is the same as the number of C2 sectors.
In the case of 256 to 510 sectors, the number of interleave divisions = 2. At this time, the number of C2 sectors per interleave (C2 / Intv), that is, the number of C2 sectors given to each of the two interleaves is an integer part obtained by dividing the number of C2 sectors by the number of divisions (= 2). Same number.
For example, in the number of sectors 256 to 258, an integer part obtained by dividing the number of C2 sectors “15” by 2 is used as the number of C2 sectors per interleave (C2 / Intv), so the number of C2 sectors in each interleave is “7”. (Indicated as “7/7” in the figure).
In addition, in the number of sectors 542 to 558, an integer part obtained by dividing the number of C2 sectors “33” by 3 is used as the number of C2 sectors per interleave (C2 / Intv), so the number of C2 sectors in each interleave is “11”. (Indicated as “11, 11, 11” in the figure).

  For example, by providing such a table, the ECC control information generation unit 26 uses the number of interleave divisions and the C2 sector in each interleave as control information for ECC block setting based on information on the number of sectors of the track to be accessed. A number can be output.

Each value in FIG. 8 can also be expressed as a calculation formula.
The C2 sector number is rounded off to the integer value for the result of sector number × redundancy.
The number of interleave divisions is 255 sector units, and when this number is exceeded, the number increases by +1.
That is, interleave division = integer part {(number of sectors−1) ÷ 255} +1
The number of C2 sectors per interleave is an integer part obtained by dividing the calculation result of the number of C2 sectors by each interleave.
That is, C2 sectors per interleave = integer part (number of sectors / number of interleaves)

In other words, by having the table data as shown in FIG. 8 or by having an algorithm for executing the above calculation formula without having the table data, the ECC control information generating unit 26 is provided with the magnetic disk 21. Control information for setting the C2 sector and interleaving can be generated and given to the disk controller 13 for each upper track.
The ECC controller 36 in the disk controller 13 performs ECC processing based on the supplied interleaving and C2 sector number information, thereby realizing ECC processing according to the track.

  As can be seen from FIG. 8, the number of C2 sectors is set based on the redundancy (for example, 6%) with respect to the number of sectors per track. Therefore, the ECC block processing being performed by this setting means that efficient ECC block processing is performed in accordance with the status of each track on the magnetic disk 21. For example, the number of sectors in each track may be different due to various circumstances, such as a change in the number of sectors due to a format according to the zone, disk surface, or head characteristics on the magnetic disk 21, and a sector loss due to an existing slip. However, by setting the number of C2 sectors and the interleave structure according to the number of sectors per track, the C2 sectors can be optimally and efficiently arranged according to the actual track situation.

By the way, in the example of FIG. 8, the number of C2 sectors per interleave is the same. For this reason, for example, the number of C2 sectors calculated with a redundancy of 6% may not be reflected as it is. For example, when the number of sectors is 256 to 258 as described above, C2 sector = 15 sectors, but C2 sectors that are actually allocated to two interleaves are 7 sectors each, resulting in 14 sectors.
On the other hand, if the condition that the number of C2 sectors is the same for each interleave is eliminated, the number of C2 sectors can be reflected in more detail.
This is shown in FIG. 9 as another example.
FIG. 9 shows an example in which the total number of C2 sectors per interleave (C2 / Intv) is allocated so as to match the number of C2 sectors calculated with a redundancy of 6%.
For example, in the case of 256 to 258 sectors, the number of C2 sectors per interleave (C2 / Intv) is set to “7.8”. That is, in one interleaved structure, 7 C2 sectors are arranged, and in the other interleaved structure, 8 C2 sectors are arranged. As a result, the number of C2 sectors in the track is set to 15 sectors.
Similarly, for example, when the number of sectors is 511 to 524, the number of C2 sectors is 31, but on the other hand, by setting the number of C2 sectors in three interleaves to “10 · 10 · 11”, a total of 31 sectors is obtained. To be.
By setting in this way, the ECC block can be set in a state closer to the intended redundancy, and a more efficient ECC configuration can be achieved.

As another example, for example, the number of C2 sectors having a predetermined redundancy is rounded off in the above description, but only the integer part of the calculation result may be used.
That is, the number of C2 sectors may be the fractional part of the result of (number of sectors × redundancy) rounded down.

Incidentally, for example, when the redundancy can be represented by (1/2 ⁿ ), it can be represented by bit notation as shown in FIG.
For example, when n = 4, 1/2 ⁴ = 1/16 = 0.0625 ... 6.25%
When n = 5, 1/2 ⁵ = 1/32 = 0.03125 ... 3.125%
It is.
When the redundancy is 6.25% or 3.125%, the number of C2 sectors is expressed as shown in FIG. 10 with respect to the number of sectors per track.
In FIG. 10, the number of sectors per track 0, 1, 2,... (Decimal notation) is represented by a 12-bit value. In that case, the number of C2 sectors for each number of sectors is a value obtained by shifting the number of sectors of 12 bits by n bits.
In other words, when the redundancy is 6.25%, the 8-bit value obtained by shifting the 12-bit value by 4 bits indicates the number of C2 sectors, and when the redundancy is 3.125%, the 12-bit value is 5 bits. The shifted 7-bit value indicates the number of C2 sectors.
In this way, the ECC control information generating unit 26 can be configured with simple hardware or a table.

  As for the number of C2 sectors with respect to the redundancy value, the actual ECC block configuration is such that the number of sectors that can be simply divided is given for each zone as in the examples of FIGS. 8, 9, and 10. Is not limited. Therefore, for example, each of the above examples is applied to a request to provide a desired range of redundancy or to provide a correction capability higher than desired, rather than to provide an ECC block configuration with complete redundancy. Should be considered.

  By performing the ECC block setting as shown in each of the above examples, the HDD 10 of this example can provide an ECC block configuration having a correction capability more suitable for the entire surface of the magnetic disk 21.

An example in which interleaving is applied to the ECC block configuration shown in the above example will be described with reference to FIGS.
Here, in the Reed-Solomon code having a symbol length of 8, generally, the maximum number 255 can be used as a processing unit, and therefore, the following example is shown.

  The example described below can be applied in the same way with a maximum of 511 for a Reed-Solomon code of symbol length 9 and a maximum of 1023 for a Reed-Solomon code of symbol length 10. Further, in the Reed-Solomon code having a symbol length of 8, it is possible to increase the maximum to 256 by performing the extension process, but in any case, the present invention can be handled in the same manner.

FIG. 11 shows an example in which interleaving is applied to track n and one track has 540 sectors.
In the case of FIG. 8, the number of interleave divisions = 3 is given to 540 sectors. Also, the number of C2 sectors is 32 sectors, but the number of C2 sectors in each of the three interleaves is 10 sectors by making the same number. That is, a total of 30 sectors are C2 sectors.
Therefore, in this case, as shown in FIG. 11A, 510 sectors are data sectors and 30 sectors are C2 sectors with respect to 540 sectors in track n.
Since the number of interleave divisions is 3, an interleave structure of interleaves 0, 1, and 2 as shown in FIG.
For example, the interleave 0 is configured by adding 10 C2 sectors to a 170 sector data sector obtained by dividing 510 sectors into three. The same applies to interleaves 1 and 2.
Then, the sector arrangement in the track is arranged in order, such as interleave 0 for the first, interleave 1 for the first, interleave 2 for the second, and interleave 0 again for the third. The C2 sectors created successively are arranged in order in the same manner after the data sector.
FIG. 11B shows an interleaved decomposition, and FIG. 11C shows an arrangement when addresses 0 to 539 are allocated on the memory.

The example of FIG. 11 corresponds to the case of FIG. 8, but corresponds to the case of FIG. 9 as shown in FIG.
In the case of FIG. 9, the number of interleave divisions = 3 is given to a track of 540 sectors. Further, the number of C2 sectors is 32 sectors, which is distributed to each of the three interleaves. That is, the number of C2 sectors in each interleave is 10.11.11. Since 32 sectors become C2 sectors, 508 sectors are data sectors relative to 540 sectors in track n.
Accordingly, the interleave structure of interleaves 0, 1, and 2 as shown in FIG.
For example, interleave 0 is configured by adding 10 C2 sectors to 170 data sectors. Interleaves 1 and 2 are configured by adding 11 sectors of C2 sectors to 169 sectors of data sectors.

The actual recording data configuration is not limited to this example. For example, header information for each sector may be included, or a CRC sector may be provided for the sector.
In any case, when the additional information is given in units of sectors, it can be similarly applied.
Also, regarding the number of bytes in one sector, at present, one sector is generally 512-byte data. However, of course, this is not the case. For example, even when 1024 bytes or 2048 bytes are used as one sector data. In the same manner as described above, ECC blocks configured for each sector and between sectors can be realized.

  As described above, the ECC block is completed in units of a predetermined number of tracks, the C2 sector is given as an ECC block under predetermined conditions based on the information on the number of sectors in the predetermined track, and the interleave configuration is By setting as described above, the redundancy of the ECC portion can be controlled within a predetermined range, so that an efficient ECC block configuration can be achieved, and random errors and bursts in a wider range can be achieved over the entire circumference of the disk. Error correction is possible even for errors, and stable data reproduction is realized.

Next, the flow of the ECC block setting process in the above example will be described with reference to FIG.
FIG. 13 shows processing realized by the operation of each unit in FIG. 1 centering on the CPU 11 and the disk controller 13 during data writing or reading.
As the pre-processing, information on the number of sectors for each track of the magnetic disk 21 is necessary, which is given in advance. The location where the sector number information is stored is, for example, a built-in memory (ROM / RAM 12 or the like) or a predetermined area of the magnetic disk 21.
First, when a write target track is set in step F101, in step F102, sector number information for the track is referred to. As described above, the reference destination is, for example, the ROM / RAM 12 or a preallocated area of the magnetic disk 21.
Next, in step F103, the function of the ECC control information generation unit 26 determines the number of C2 sectors and interleave contents (number of divisions and C2 sector allocation in each interleave) from the obtained sector number information. Refer to a table as shown in FIG. Note that, as described above, a calculation process of a predetermined calculation formula may be performed without using a table.
By the process of step F103, the number of C2 parities in the track is determined and the interleave setting is also determined in step F104.
In step F105, control information indicating the content determined in step F104 is sent from the ECC control information generation unit 26 to the ECC controller 36 and the like, and the ECC block format for the corresponding track is determined. Then, the process proceeds to the writing or reading process.
At the time of writing, the ECC controller 36 generates an ECC block according to the instructed number of C2 sectors and interleave contents. Then, the process proceeds to the writing process.
When reading, the ECC controller 36 determines the ECC block format according to the instructed number of C2 sectors and interleave contents. Thereafter, error correction processing is performed on the data read from the corresponding track in the ECC block format.
Note that the number of C2 sectors and the interleave contents as the ECC block format are matched in recording and reproduction so that normal processing is realized.

5). Application examples

The present invention is not limited to the above-described example, and can be applied to various cases as follows.
The number of magnetic disks 21 in the HDD is shown as being two, but the present invention is naturally applicable to cases where the number is one or more than three. Not only the configuration of the magnetic disk 21 and the head 22 and the like, but an ECC block is set according to the number of sectors of the track (or unit), so that an efficient ECC block corresponding to the situation of the track of the magnetic disk, etc. Is realized.

  In the process of FIG. 13, the number of sectors information of each track is stored in advance in the ROM / RAM 12 (or a predetermined area of the magnetic disk 21), but the number of sectors is not the number of sectors per track. Depending on the track number, the number of C2 sectors or the interleave content itself may be recorded corresponding to the track number.

Further, FIG. 1 shows the portion of the ECC control information generation unit 26 inside the hard disk device 10, but the ECC control information generation unit 26 is not limited to this position. It may be configured in an independent part inside and outside the hard disk device, and the number of C2 sectors and the like may be controlled using necessary information.
For example, the host controller may be provided with a function as the ECC control information generation unit 26 and may be controlled via the external interface 17.

In FIGS. 8 and 9, the maximum number of sectors per track is shown up to 1020. However, it is natural that the same effect can be obtained even if a larger number of sectors is given according to the above calculation formula. Also, the number of interleaves is the same when the number is 5 or more.
Further, in each example, the redundancy is shown as fixed 6%. However, for example, the error correction capability may be increased by increasing the redundancy in a specific area. In any case, it is the same that the number of C2 sectors is determined from the redundancy determined in these tables. Further, changing the redundancy means that it becomes possible to have a detailed structure with respect to the characteristics of the disk or the contents of the data in more detail.

  The present invention is not limited to the HDD, and the present invention can be applied to other types of disc recording / reproducing apparatuses. For example, the present invention can be applied to a system in which a track has a spiral shape in addition to a concentric track shape. Of course, the present invention can be applied not only to magnetic disks but also to systems for optical disks and magneto-optical disks.

The program of the present invention is a program for realizing the functions of the HDD 10 described above. In particular, the processing shown in FIG. 13 is executed by being started up by the CPU 11 and controlling each part of the HDD 10 based on the program.
This program can be stored in advance in the ROM / RAM 12, for example. Alternatively, a form in which the data is stored in the magnetic disk 21 and loaded into the ROM / RAM 12 is also conceivable.

It is a block diagram of the whole structure of HDD of embodiment of this invention. It is explanatory drawing which showed typically the disc format structure of embodiment. It is a block diagram of a disk controller of the HDD of the embodiment. It is explanatory drawing of the error correction range of embodiment. It is explanatory drawing of the conversion table for the access of embodiment. It is explanatory drawing of the ECC block used as the track unit of embodiment. It is explanatory drawing of the ECC block structure of embodiment. It is explanatory drawing of the table which generate | occur | produces ECC block control information of embodiment. It is explanatory drawing of the other example of the table which generate | occur | produces ECC block control information of embodiment. It is explanatory drawing of the example which obtains the C2 sector number with respect to the track sector number of embodiment by a bit shift. It is explanatory drawing of the interleave structure of embodiment. It is explanatory drawing of the interleave structure of embodiment. It is a flowchart of the ECC block setting process of an embodiment.

Explanation of symbols

  10 HDD (Hard Disk Device), 11 CPU, 12 ROM / RAM, 13 Disk Controller, 14 Buffer RAM, 15 Data Read / Write Control Unit, 16 Servo Control Unit, 21, 21a, 21b Magnetic Disk 22, 22a, 22b Magnetic Head, 26 ECC control information generator

Claims (19)

Concentric or spiral tracks are formed, and each track is a data recording / reproducing apparatus for a disk recording medium divided into a plurality of sectors,
Seek means to seek the target track;
Data access means for accessing on the sought track;
Error correction means for generating an error correction code for error correction of the data and correcting the error of the data based on the error correction code;
Control information generating means for generating control information of an error correction block corresponding to access by the data access means to the disk recording medium,
The control information generating means generates the control information according to the number of sectors in a unit of predetermined processing data, which is adapted to an image or sound in a range accessed by the data access means,
The error correction means sets a first error correction code unit for a predetermined data amount unit, sets a second error correction code unit for a plurality of first error correction code units, and sets a plurality of error correction code units. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and setting the number of sectors of the second error correction code unit is as follows: A data recording / reproducing apparatus, characterized in that it is performed based on the control information generated by the control information generating means.   2. The control information generating means generates the control information indicating the number of sectors in the second error correction code unit according to the number of sectors in the range accessed by the data access means. The data recording / reproducing apparatus described in 1. The control information generating means generates the control information indicating interleave contents according to the number of sectors in the range accessed by the data access means,
2. The data recording / reproducing apparatus according to claim 1, wherein the error correction unit generates an error correction block having an interleave structure according to an instruction of the interleave contents. The control information generating means comprises a data table storing the number of sectors and the number of sectors of the second error correction code unit corresponding to the number of sectors,
3. The control information indicating the number of sectors in the second error correction code unit is generated by referring to the data table in accordance with the number of sectors in the range accessed by the data access means. The data recording / reproducing apparatus described in 1.   The control information generating means generates the control information indicating the number of sectors in the second error correction code unit by an arithmetic process on the number of sectors in the range accessed by the data access means. 2. The data recording / reproducing apparatus according to 2.   The number of sectors in the second error correction code unit is a positive integer derived from a numerical value calculated by a predetermined redundancy ratio with respect to the number of sectors in the range accessed by the data access means. The data recording / reproducing apparatus according to claim 4 or 5. The control information generating means includes a data table storing the number of sectors and the number of interleave divisions corresponding to the number of sectors,
4. The data recording / reproducing apparatus according to claim 3, wherein the control information indicating the number of interleave divisions is generated by referring to the data table in accordance with the number of sectors in the range accessed by the data access means. .   4. The data recording / reproducing apparatus according to claim 3, wherein the control information generating means generates the control information indicating the number of interleave divisions by arithmetic processing on the number of sectors in the range accessed by the data access means. .   The control information generating means generates the control information indicating the number of sectors in the second error correction code unit and the number of interleave divisions according to the number of sectors in the range accessed by the data access means, and 2. The data recording / reproducing apparatus according to claim 1, wherein when the number of interleave divisions is two or more in the control information, the number of sectors in the second error correction code unit in each interleave is the same.   2. The data recording / reproducing apparatus according to claim 1, wherein the error correction means generates an error correction code by a Reed-Solomon code method. As a data recording / reproducing method for a disk recording medium in which concentric or spiral tracks are formed and each track is divided into a plurality of sectors,
Seek step to seek the desired track;
A data access step for accessing on the sought track;
An error correction step for generating an error correction code for error correction of the data and error correcting the data based on the error correction code;
A control information generation step for generating control information of an error correction block corresponding to access by the data access step to the disk recording medium,
In the control information generation step, the control information is generated according to the number of sectors in a unit of predetermined processing data, which is adapted to the image and sound in the range accessed in the data access step,
In the error correction step, a first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of error correction code units are set. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and setting the number of sectors of the second error correction code unit is as follows: A data recording / reproducing method characterized in that it is performed based on the control information generated in the control information generating step.   12. The control information generation step generates the control information indicating the number of sectors in the second error correction code unit according to the number of sectors in the range accessed in the data access step. The data recording / reproducing method described in 1. In the control information generation step, the control information instructing the interleave contents according to the number of sectors in the range accessed in the data access step is generated,
12. The data recording / reproducing method according to claim 11, wherein in the error correction step, an error correction block having an interleave structure corresponding to an instruction of the interleave content is generated.   12. The data recording / reproducing method according to claim 11, wherein in the error correction step, an error correction code is generated by a Reed-Solomon code method. A program written in a computer-readable format for executing data recording / reproduction processing on a disk recording medium on which a concentric or spiral track is formed and each track is divided into a plurality of sectors on a computer system As
Seek step to seek the desired track;
A data access step for accessing on the sought track;
An error correction step for generating an error correction code for error correction of the data and error correcting the data based on the error correction code;
A control information generation step for generating control information of an error correction block corresponding to access by the data access step to the disk recording medium,
In the control information generation step, the control information is generated according to the number of sectors in a unit of predetermined processing data, which is adapted to the image and sound in the range accessed in the data access step,
In the error correction step, a first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of error correction code units are set. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and setting the number of sectors of the second error correction code unit is as follows: A program that is performed based on the control information generated in the control information generation step.   16. The control information generation step generates the control information indicating the number of sectors in the second error correction code unit according to the number of sectors in the range accessed in the data access step. The program described in. In the control information generation step, the control information instructing the interleave contents according to the number of sectors in the range accessed in the data access step is generated,
16. The program according to claim 15, wherein in the error correction step, an error correction block having an interleave structure corresponding to the instruction of the interleave content is generated.   18. The program according to claim 17, wherein in the error correction step, an error correction code is generated by a Reed-Solomon code method. A first error correction code unit is set for a predetermined data amount unit, a second error correction code unit for a plurality of first error correction code units is set, and a plurality of the first error correction code units are set. An error correction block including a correction code unit and the second error correction code unit added thereto is formed. In the error correction block, the second error correction code unit is a data write / read It is set based on the number of sectors in the unit of predetermined processing data, which is adapted to images and audio in the range where read access is performed,
A recording medium, wherein the data having the error correction block configuration is recorded on a concentric or spiral track.

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