JP3477800B2 - Disk drive device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for, for example, a hard disk drive or an optical disk drive having a writable optical disk.
About the location.

[0002]

2. Description of the Related Art A lossless coding compression technique (also called entropy coding or lossless coding) that completely restores compressed data when decompressed can increase the apparent data recording capacity of an external storage device such as an optical disk drive. So it is a technology that is drawing attention.

Conventionally, this data compression function is built in the host computer. However, in a system in which multiple disk drives (hereinafter also simply referred to as drives) are connected to the host computer, when different data is transferred from the host computer to these multiple drives, data compression is performed. Since a huge amount of calculation time is required, it takes a considerable amount of time to finish the data transfer to all the drives.

In other words, when different data are transferred to a plurality of drives, the host computer is dedicated to the data compression process, and other processes cannot be performed. Further, as a matter of course, only the drive connected to the host computer having the data compression function can increase the apparent data recording capacity. Further, there is an inconvenience that a drive having a disc on which compressed data is recorded can be reproduced only by a host computer having a decompression function.

When recording data in a drive as an external storage device, first, the host computer has a data recording capacity (also referred to as a data storage capacity, a data recording size or a data storage size) on a disk in the drive. You need to know what remains. This is to confirm in advance whether or not the size of the data to be recorded can be actually recorded. In such a case, for example, SCSI (Small Computer Systenr Int
erface) between the host computer and the drive, the host computer as the initiator issues a read capacity command to the drive as the target.

The drive has a data compression function (built-in)
Assuming that the data is actually recorded, the recording capacity of the data physically remaining in this drive is the data recording capacity for the compressed data. On the other hand, what the host computer wants to know is how much uncompressed data can be recorded. In this case, if the data compression rate is always constant, the relationship of these capacities is always the same in a linearly proportional relationship, so that the data compression rate n, for example, n = 2, is the remaining physical data. It is simple because the data recording capacity multiplied by the recording capacity may be reported to the host computer as the remaining data recording capacity.

However, this is not a compression technique with a loss that may be adopted in the case of digital data such as audio data or image data obtained by converting an analog signal, for example, a compression technique using a well-known discrete cosine transform technique. A lossless coded data compression technique for reliably processing data that needs to be expanded to the same data as the input data, for example, the well-known Huffman coding technique or Lempel-Ziv (LZ = Lempel-Tiv) coding technique, Varies depending on the content of the supplied data (for example, how much the same term, the same expression, etc. are used in the data) and is not constant.

Therefore, in a drive equipped with a reversible encoding compression technique, the compression rate is predicted, and based on the estimated compression rate and the physically remaining data recording capacity, how much data before compression is recorded. It will report to the host computer what can be done.

[0009]

However, when the actual compression rate is smaller than the expected compression rate (bad),
There is a possibility that all the data to be recorded cannot be recorded and the data will be lost. That is, if the host computer believes the apparent data recording capacity reported by the drive and transfers the data to the drive without storing it in a buffer in the host computer,
Data already transferred to the drive may be lost.

Although the host computer manages the data as if it is not compressed, in reality, the data is compressed and recorded on the disk, and the compression rate is not constant. Therefore, for example, if files of the same size are recorded consecutively and there is no compression, use a simple calculation such as (fixed value) × (constant) of (file size) × (number of files). For example, it is possible to speed up the access for reading the data recorded in the drive.

However, when there is compression, the size of the original file before compression is usually not the same as the size of the file after compression. Therefore, by using such a simple calculation, high-speed access can be achieved. It cannot be realized.

The present invention has been made in consideration of such a problem, and enables efficient management of data having a non-constant compression ratio, and also when the compression ratio becomes smaller than expected. It is an object to provide a disk drive device that is unlikely to be lost.

It is another object of the present invention to provide a disc that enables efficient management of recorded compressed data.

[0014]

According to a first aspect of the present invention, there is provided data compression means 13 for converting uncompressed data supplied from a host computer 10 into compressed data by a lossless coding compression technique. upon recording on the disc 1, and the logical address of the pre-compression data received from the host computer 10, together with the corresponding is allowed allocation correspondence table FAT and a physical address of data after compression to be recorded on the disk 1 is recorded on the disk 1 ,disk
When it becomes smaller actual compression ratio than expected compression ratio in the drive apparatus main body, the size of data after compression when more remaining data recording capacity only, special recording area for recording data after compression Is previously provided on the disc.

A second aspect of the present invention is an allocation correspondence table FA
The contents of T are recorded as uncompressed data.

[0016]

A third aspect of the present invention uses a special recording area as a replacement area.

In a fourth aspect of the present invention, when the disc is a rewritable disc 1 and there is no access from the host computer 10, the arrangement of the recording positions of the compressed data already recorded on the disc 1 is assigned. The correspondence table FAT is used.

In a fifth aspect of the present invention, when a command for confirming the remaining data recording capacity on the disk 1 is issued from the host computer 10, the expected compression rate is corresponding to the decrease in the unrecorded data recording capacity on the disk 1. The apparent data recording capacity with a reduced value is reported to the host computer.

[0020]

[0021]

According to the first aspect of the present invention, when the compressed data reversibly encoded and compressed by the data compression means is recorded on the disk, it is recorded on the disk and the logical address of the uncompressed data received from the host computer 10. An allocation correspondence table that associates the physical addresses of the compressed data with each other is recorded on the disk, and the disk drive device
When it becomes smaller than expected compression rate by Ri actual compression ratio at Okimoto body, the size of data after compression when more remaining data recording capacity only, a special recording area for recording data after compression Since it is provided on the disk in advance, it enables efficient management of compressed data with a non-constant compression ratio, and the compression ratio is smaller than expected.
There is almost no chance of losing data even if it is not .

According to the second aspect of the invention, since the contents of the allocation correspondence table are recorded as uncompressed data, it is not necessary to read the contents of the allocation correspondence table and then expand the contents. You can understand the contents of the table in a short time.

[0023]

According to the third aspect of the invention, since the special recording area is used as the replacement area, the disc can be used efficiently.

According to the fourth aspect of the invention, when there is no access from the host computer, the allocation correspondence table is used to organize the recording positions of the compressed data recorded on the rewritable disc. Therefore, the subsequent access can be speeded up.

According to the fifth aspect of the present invention, when the host computer issues a command for confirming the remaining data recording capacity on the disc, the expected compression ratio is set in accordance with the decrease in the unrecorded data recording capacity on the disc. Since the reduced apparent data recording capacity is reported to the host, there is almost no possibility of losing data even when the compression rate is smaller than expected.

[0027]

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing the configuration of an optical disk drive device 11 to which this embodiment is applied.

The optical disk drive device 11 has a CPU (central processing unit) 21 which is a system controller. A data compression (encoding) means unit 13 for converting the data before compression supplied from the host computer 10 into the data after lossless encoding and compression (simply referred to as compressed data) is connected to the bus 12 to which the CPU 21 is connected.
And a data decompression (decoding) means 14 for restoring the compressed data to the original. The compression means 13 and the expansion means 14 can be configured by a microcomputer or the like.

Since the reversible coding compression technique itself is not directly related to the present invention, it will not be described in detail, but the compression means 13 and the decompression means 14 can use the compression technique by the LZ method, for example. The compression technique by the LZ method will be briefly described. It is a system that uses a conversion table for converting an input character (data) string into a code. That is, the input character string is read and converted (encoded) into, for example, a 26-character code that is registered in a dictionary (hereinafter, also referred to as a basic conversion table) in advance, while being registered in this basic conversion table. This is a method of creating and registering a new dictionary (hereinafter also referred to as a creation conversion table) for a character string that does not exist. While updating and using this creation conversion table, the input character string is compressed and decompressed. In other words, it is a method of expanding a compressed character while creating a creation conversion table from the compressed character string at the time of decoding.

The ROM (read only memory) 23 includes
A software program for system control etc. is recorded and held. A RAM (random access memory) 22 is a work RAM of the CPU 21. In addition,
It is also used as a work RAM for the compression means 13 and the expansion means 14.

The command issued from the host computer 10 is sent to the CPU 2 through the host interface 20 such as SCSI, the buffer controller 24 and the bus 12.
Sent to 1.

The CPU 21 performs processing corresponding to this command. As the command, for example, the read capacity command disk 1 for confirming how much recording capacity remains in the optical disk (hereinafter, also simply referred to as a disk) 1 in the optical disk drive device 11 is initialized. There are a disk certify command, a well-known read command, a write command, a write & (and) verify command, etc.

In order to describe the structure of the disc 1 and the optical disc drive apparatus 11 as a whole, a case where a disc certify command is supplied from the host computer 10 will be described as an example. It should be noted that the compression unit 13 and the decompression unit 14 do not operate at the time of disk formatting by the disk certify command.

The CPU 21, which has received the disk certify command, reads the data for performing the disk certify processing from the ROM 23, and writes the read data to the data buffer 25 through the buffer controller 24.

FIG. 2 shows an example of the disk format of the disk 1. There are 10,000 tracks having track numbers (track addresses) “0” to “9999” from the outer side (outermost side) in the radial direction toward the inner side (innermost side). In the following description, the track numbers will be simply referred to as tracks 0 to 9999 or track addresses 0 to 9999 as needed.

Track 0 to Track 2 and Track 99
48 to 9999 are optical disk drive devices 11
It is a track managed only by the CPU 21 of.
Among them, the tracks 9948 to 9996 are replacement areas AE, as will be described later, and the tracks 0 to 2 and the tracks 9997 to 9999 are called drive areas DE in the sense that the optical disk drive device 11 manages them, and the remaining tracks. Tracks 3 to 9947 are user areas UE.

The drive area DE is preferably recorded with uncompressed data. This is to speed up access to processing such as read or write, as will be described later. In addition, in the user area UE and the replacement area AE,
The compressed data compressed by the compression means 13 is recorded.

Each track has a physical sector number "0" to
Sectors of “24” (Physical sectors 0 to 24 if necessary or, if the meaning is clear from the front and rear relationships, simply sectors 0 to 24)
Also called 24. Also called a sector address. )have. Memory capacity of one sector (data recording capacity)
Is 2048 B (bytes). In this embodiment, the host computer 10 is designed to record or read data in units of 100 sectors. In this sense, 100 units × 2 kB = 200 kB as the recording unit and data recording capacity for 100 sectors is called block data.

In other words, in this embodiment, the host computer 10 is composed of the 100 sectors 20.
Data is managed in units of block data of 0 kB. In this case, the host computer 10 manages the sector 0 of the track 3 of the user area UE as the start address 1 of the block data, and hereinafter, every 100 sectors, the start address of each sector is set to the sector address 10.
It will be managed in order as 1, 201, .... However, in reality, since the data recorded in the user area UE is compressed data, the address of the block data managed by the host computer 10 and the address on the disk 1 do not uniquely correspond to each other. In this sense, the address managed by the host computer 10 is a logical address (logical sector address), and the optical disk drive device 11
The address managed by is called a physical address (physical sector address). It is an object of the present invention to make it possible to easily manage the correspondence between the logical address of block data before compression and the physical address of block data of compressed data.

Referring again to FIG. 2, sector 0 of track 0, sector 12 of track 1, sector 0 of track 9997, and sector 12 of track 9998 are DDS (disk definition structure) sector # 0.
~ # 3. Track 0 Sector 1, Track 1 Sector 13, Track 9997 Sector 1 and Track 9
Sectors 13 of 998 are PDL (Primary Defect List) sectors # 0 to # 3 in which information of defective sectors (also referred to as defective sectors or error sectors) at the time of disc certification is recorded.
The sector 2 of track 0, the sector 14 of track 1, the sector 2 of track 9997, and the sector 14 of track 9998 record the defect sector information after the disk certify, for example, at the time of write & verify, SDL. (Secondary defect list) Sectors # 0 to # 3.

Then, the CPU 21 which receives the disk certify command is operated by the servo controller 2
7, the sector 0 of the track 3 of the user area UE
From the data buffer 25 to the buffer controller 24 at the same time as the trial write instruction from the
Through the drive interface 26. At the same time, the drive interface 26 is also instructed to write on the disc 1 through the optical pickup 29.

In the present embodiment, the fixed sector portion is
Since the host computer 10 is designed to manage block data in units of 100 sectors, this 1
The recording unit for 00 sectors may be a fixed sector.

Then, the optical pickup 29 and a magnetic head (not shown) are moved through the linear motor 17 to the target track (a certain sector from the sector 0 of the track 3) of the disk 1 rotated by a spindle motor (not shown). Due to the interaction between the light L and the magnetic field from the magnetic head (known technique), the writing for the certain sector is completed.

When the writing is completed, the CPU 2
1 is the reverse direction of the data flow (disk 1
To the data buffer 25) A read command is issued from the sector 0 of the track 3 to the above-mentioned fixed sector for the buffer controller 24 and the drive interface 26
And instruct the servo controller 27.

As a result of the read based on this read command, if all of these fixed sectors are normal sectors,
Writing and reading for a certain sector are performed again from the next sector for the certain sector. In this way, reading and writing are repeated until the final sector (sector 24 of the track 9996 in the replacement area AE). If a read error is found in the middle of reading / writing, the sector to be replaced is replaced by the replacement area A.
Allocations are sequentially made from sector 0 of track 9948 in E, and the allocation information is written and registered in PDL sector # 1.
The compressed data which is to be recorded in the defective sector is recorded in the replacement area AE. When an access to the error sector occurs after the disk certify, the PDL sector # 1 is referenced to access the replacement sector.

When the CPU 21 checks all the sectors in the user area UE and the replacement area AE of the disc 1, the tracks 0 and 1 and the tracks 9997 and 999 are checked.
8 DDS sectors # 0 to # 3 and PDL sectors # 0 to # 3
And SDL sectors # 0 to # 3 write the same information (DDS sectors # 0 to # 3 have the same contents, PDL
Sectors # 0 to # 3 have the same contents and SDL sectors # 0 to # 3
(The meaning of # 3 is the same). At this point, that is,
At the time of the disk certify processing, the defect sector information is not written in the SDL sectors # 0 to # 3.

In this way, the same data is written in four locations because of these DDS sectors # 0 to #.
3, PDL sectors # 0 to # 3 and SDL sectors # 0 to #
For backup of the data recorded in 3 (backup copy: copy the same data to a non-volatile memory (in this case, the disk 1 which is an MO disk) so that the data is not accidentally lost) Is.

Thus, the disk certify operation is completed.

FIG. 3 shows a part of allocation contents in the DDS sector. The first 2 bytes of byte numbers 0 and 1 are
The content indicates the ID (identification part) of the DDS sector, and "0A" (hexadecimal representation of BCD) is recorded in the 2 bytes. Byte numbers 2, 2047, etc. are reserved (undefined), and "00" is recorded. Byte number 3 records whether or not a disk certify has been performed. If it has already been completed, "01"
Is recorded, and if it has not been performed yet, “02” is recorded. Therefore, the recording data of the byte number 3 of the DDS sector is rewritten from "02" to "01" at the end of the disc certify operation.

For the byte numbers P, P + 1, ..., P + Q, the logical address of the uncompressed data received from the host computer 10 and the disk 1 are recorded in the recording data column.
An allocation correspondence table FAT for recording the user area UE and the physical area of the compressed data recorded in the replacement area AE in association with each other. The data is recorded in this allocation correspondence table as uncompressed data as described above.

Next, regarding the main operation of this embodiment, RO
Program flow chart of recording procedure, flow chart of read procedure and DD recorded and held in M23
The S sector allocation correspondence table FAT will also be described with reference to an example.

FIG. 4 is a flow chart provided for explaining the recording procedure. FIG. 5 is a flowchart provided for explaining the reading procedure. FIG. 6 shows the allocation correspondence table F.
This is an example of AT.

In the description of the recording procedure shown in FIG. 4, it is assumed that the above-mentioned disc certifying process has been completed. Therefore, when the optical disk drive device 11 is powered on (step S1), the drive area D
DDS sectors # 0 to # 3 and PDL sectors # 0 to # in E
3 and the contents of SDL sectors # 0 to # 3 are read into the RAM 22 (step S2). As a result, RA
M22 functions as a cache memory for these read contents.

Next, a recording request, that is, a write command is issued from the host computer 10 (step S).
3). Next, the start address 4 of the block data as a logical sector address managed by the host computer 10
A set of data consisting of two block data (data before compression) of 200 sectors from 901 (see FIG. 6) to the end address 5100 of the block data is transferred from the host computer 10 to the optical disk drive device 11.
Data buffer 25. This set of data is the data that the host computer 10 is about to record on the disc 1 from now on.

In this embodiment, the size of one block data is 100 sectors × 2 kB = 200 kB since it is 100 sectors worth of data as described above. Therefore, a = 4901 and c = 50 are stored in the head address columns (head logical address column) a and c of the block data in the data management information column for the host on the FAT allocation correspondence table.
The start address of the block data of 01 is written, and b is entered in the end address columns b and d of the block data.
= 5000, d = 5100, the end address of the block data is written. At this point, this logical address is not written in the DDS sector of the disk 1, but the DD in the RAM 22 from which it is read.
It is written in the allocation correspondence table FAT in the S sector.
The RAM 22 in which the allocation correspondence table FAT is recorded is used as a so-called cache memory.

Next, this block of the two block data is compressed block by block by the compression means 13 (step S4). In this case, it is assumed that each block data is compressed to about twice the compression ratio n = 2.

The size of the compressed data can be specified by this step S2. In this case, 50 sectors worth of data is 100 kB worth of data.

Next, the currently available recording area in which the compressed data can be recorded is searched from the allocation correspondence table FAT (step S5). Needless to say, the usage status (free information) of the disk 1 may be managed in another place on the DDS sector other than the allocation correspondence table FAT. Here, the usage status of the column of the data management information on the disk 1, that is, from the recorded physical address of the column of the data management information on the disk 1 in FIG.
50 sectors up to 2050 and physical sectors 3561-4
It is assumed that 50 sectors up to 110 are unrecorded areas.

Therefore, the compressed data is recorded in these sectors in the user area UE on the disc 1 (step S6).

In this case, the allocation table F on the RAM 22
Physical sectors 2001 to 2050 shown in AT columns e and f
Also, since the data of 100 sectors from physical sectors 3561 to 4110 shown in columns h and i is originally a set of data, the data next to sector 2050 is stored in sector 3561 in link information column g in the allocation correspondence table FAT. Link sector information "3561" indicating that it is recorded
Write down. In addition, “FF” is recorded in the link sector information column j next to the sector address 4110 at the end of the block data as the link sector information to indicate the end of the set of data. In this way
The allocation table FAT on the RAM 22 is created or updated (step S7).

In columns k to o, the logical sector address 100 is set as the logical address of the host computer 10.
It can be seen that compressed data of one block data of 01 to 10100 is recorded in physical sectors 5001 to 5040 which are physical sector addresses on the disk 1. In this case, the actual compression ratio an is an = 2.5.

The contents of the allocation table FAT on the RAM 22 thus updated are recorded at the positions of the allocation table FAT of the DDS sectors # 0 to # 3 of the disk 1 (step S8), and a series of recording procedure is performed. Ends.

In the state shown in FIG. 6, a set of block data represented by the logical sector addresses 4901 to 5100 is the physical sector address 2 on the disk 1.
Positions on the disk 1 are divided and recorded in data for 50 sectors starting from 001 and data for 50 sectors starting from a physical sector address 3561.

In this way, when the data is divided and recorded at the positions distant from each other on the disc 1, the disc 1 is recorded.
An additional seek time is required when reading data from the memory, resulting in a longer access time.

Therefore, when there is no access from the host computer 10, the CPU 21 refers to the allocation correspondence table FAT and arranges the recording positions of the block data divided and recorded in this way. To do. Specifically, for example, the physical sector address 2051
If ~ 2100 is empty, the compressed data of the physical sector addresses 3561 to 4110 is moved to that address. Alternatively, 100 sectors of the compressed data (a total of 50 sectors 2001 to 2050 and a total of 50 sectors 3561 to 4110) may be moved to another data recording position. By doing so, access becomes easy even when the CPU 21 views the allocation correspondence table FAT. That is, the physical sector address 2001
This is because if 100 sectors are designated, the recording addresses of the compressed data with respect to the logical sector addresses 4901 to 5100 can be designated.

Although the rewritable magneto-optical (MO) disk is used as the optical disk 1 in the above embodiment, it is needless to say that the present invention can be applied to a hard disk which is a magnetic disk. When applied to a WORM (write once read multiple) disc that can be written only once, it is possible to perform a process of moving to a completely different data recording position. However, this process is not normally performed (may be performed), but the technique of recording the allocation correspondence table FAT on the disk 1 can be applied.

Next, the reading procedure will be described.

When the optical disk drive 11 is powered on (step S11), the DDS sector # 0
To # 3, PDL sectors # 0 to # 3 and SDL sector # 0
~ # 3 is read into the RAM 22. Therefore, at this time, the allocation correspondence table FAT is also read into the RAM 22 (step S12).

Next, when a read request, that is, a read command is issued from the host computer 10 (step S13), the allocation correspondence table FAT in the RAM 22 is referred to (step S14), and the allocation table FAT is used. The logical address related to the read request is converted into a physical address (step S15).

This conversion will be specifically described. When a read command for a set of data for 200 sectors from the logical sector addresses 4901 managed by the host computer 10 is issued, the CPU 21 refers to the allocation correspondence table FAT in the RAM 22 and refers to the logical sector addresses 4901 to 200. A logical address of a set of data for sectors is converted into physical addresses representing 50 sectors from physical sector addresses 2001 and physical sectors addresses 3561 recorded on the disk 1 to 50 sectors.

Based on this physical address, first, physical sector addresses 2001 to 50 of the disk 1 are recorded.
The compressed data recorded in the sectors is read by the optical pickup 29 (step S16), and the decompressing means 1 reads it.
4, the compressed data is expanded. Decompressed data, in other words, data corresponding to data before compression is temporarily stored in the data buffer 25. Next, the compressed data for 50 sectors from the remaining physical sector address 35561 is similarly decompressed and stored in the data buffer 25 (step S
17).

The data corresponding to the uncompressed data stored in the data buffer 25 is transferred to the host computer 10 through the buffer controller 24 and the host interface 20 as a set of data (step S1).
8). This completes the reading procedure.

Next, another embodiment will be described.

When a read capacity command for confirming the remaining data recording capacity on the disk 1 is issued from the host computer 10, the CPU 21 normally causes the CPU 21 to know the total data recording size of the user area UE [this is: For example, it can be calculated from the data (the number of tracks in the user area UE and the number of sectors per track) that is recorded in advance in an appropriate area on the disc 1 as a prepit. ] To the allocation correspondence table FA in the RAM 22
By subtracting the used physical sector address referring to the data management information column on the disk of T, the remaining
In other words, the unrecorded physical data recording capacity (X [k
B], and hereinafter simply referred to as XkB. ) Can be calculated.

Then, the expected compression rate nf × remaining physical data recording capacity X = remaining logical data recording capacity Y is calculated, and the remaining logical data recording capacity Y of the calculation result is Y =
Notify the host computer 10 as nf.XkB.

As a result, the host computer 10
At present, the maximum is the remaining logical data recording capacity Y
It can be recognized that minute data can be recorded on the disc 1. In this embodiment, the expected compression rate nf is nf = 2.

However, in the data compression by the lossless encoding, the data compression rate is not constant and the accurate data compression rate cannot be known until after the compression.
If the remaining data recording capacity on the disk 1 is managed by f · X = Y), the host computer 10 may, for example, set the remaining maximum uncompressed data Y to the same capacity (same size) as the data Y. When the data is transferred to the optical disk drive device 11, the actual compression rate af of this data is the expected compression rate n.
If the value is less than f, there occurs a situation in which all the transferred data before compression cannot be recorded on the disc 1.

Therefore, in order to avoid this, when the actual compression rate af becomes smaller than the expected compression rate nf, the size of the compressed data is the remaining physical data recording capacity X.
In the above case, a special recording area for recording the data overflowing after the compression is provided on the disc 1 in advance. This special recording area is, for example, a recording area 100 sectors back from the sector 24 of the last track 9947 of the user area UE. This 100
The sector portion is a recording area (capacity) to be hidden in the host computer 10, which is subtracted from the remaining physical data recording capacity X when the CPU 1 calculates the remaining logical data recording capacity Y.

Incidentally, since the replacement area AE is usually designed so that even when the user area UE is completely used, there is still a sufficient area remaining, so the above-mentioned recording area to be hidden is left over. Replacement area AE
May be By doing so, the recording capacity of the user area UE does not become small.

As another technique for avoiding a situation in which it becomes impossible to record all the transferred data Y before compression on the disk 1, a read capacity command is issued from the host computer 10. In such a case, the apparent logical data recording capacity in which the expected compression rate nf is reduced in response to the decrease in the physical unrecorded data recording capacity on the disk 1 may be reported to the host computer 10.

FIG. 7 is drawn to explain this. When the physical unrecorded data capacity Y is from the maximum recording capacity to a constant value, the expected compression rate nf is nf = 2, and the physical compression is performed from the constant value. The expected compression rate nf is gradually reduced toward the unrecorded data capacity of 0. For example, when the physical unrecorded data capacity Y remains 10 MB, it is reported to the host computer 10 that 20 MB remains, but when only 1 MB remains,
It is possible to report that 1.5 MB remains. This makes it possible to reduce the probability that the compressed data will overflow from the optical disk drive 11 even when the maximum amount of the remaining unrecorded data capacity Y is sent from the host computer 10.

As the value of the expected compression rate nf, the actual compression rate af may be stored and replaced with the stored actual compression rate af at the next access. is there. In that sense, the expected compression rate nf may be recorded in the DDS sector of the disk 1 and controlled so as to be updated.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0085]

As described above, according to the first aspect of the present invention, when the compressed data compressed by the data compression means by the lossless encoding is recorded on the disk, the logic of the uncompressed data received from the host computer is used. Address,
If the allocation correspondence table and a physical address of data after compression to be recorded on the disc is made to correspond to recorded on the disk
Both when it becomes smaller actual compression ratio than expected compression ratio definitive in the disk drive unit main body, the size of data after compression when more remaining data recording capacity only, special for recording data after compression The recording area of is recorded on the disc in advance. This allows
The logical address from the host computer can be easily converted into the physical address on the disk managed by the disk drive device by referring to the contents of this allocation correspondence table. Therefore, the data compression on the disc drive device is able to operate efficiently, and with the data compression ratio allows for efficient management of the compressed data not constant, when the compression ratio is small Ri by expected The effect is achieved that there is almost no possibility of losing data.

According to the second aspect of the present invention, the contents of the allocation correspondence table are recorded as uncompressed data. Therefore, the contents of the allocation correspondence table can be read and understood in a short time. In other words, there is an effect that it can contribute to speeding up of access.

[0087]

According to the third aspect of the invention, the special recording area is used as the replacement area. Therefore, the effect that the disc can be used efficiently is achieved.

According to the fourth aspect of the present invention, when there is no access from the host computer, the allocation correspondence table is used to organize the recording positions of the compressed data recorded on the rewritable disc. I have to. By doing so, it is possible to obtain the effect that the subsequent access can be speeded up.

According to the fifth aspect of the present invention, when the host computer issues a confirmation command of the remaining data recording capacity on the disc, the expected compression ratio is set in accordance with the decrease in the unrecorded data recording capacity on the disc. The reduced apparent data recording capacity is reported to the host. Therefore, there is almost no possibility of losing data even when the compression rate is smaller than expected.

[0091]

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a recording format of a disc.

FIG. 3 is a diagram provided for explaining recorded contents of a DDS sector.

FIG. 4 is a flowchart used to explain the creation of an allocation correspondence table.

FIG. 5 is a flowchart provided for explaining the use of the allocation correspondence table.

FIG. 6 is a diagram showing the contents of an allocation correspondence table.

FIG. 7 is a diagram used for explaining the operation of another embodiment.

[Explanation of symbols]

1 optical disc 10 Host computer 11 Optical disk drive 13 compression means 14 Extension means FAT allocation correspondence table

Continuation of front page (56) Reference JP-A-2-42685 (JP, A) JP-A-5-242477 (JP, A) JP-A-5-346879 (JP, A) JP-A-5-122655 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 20/10

Claims (5)

(57) [Claims] 1. A data compression means for converting uncompressed data supplied from a host computer into compressed data by a reversible coding compression technique, and the compression received from the host computer when the compressed data is recorded on a disk. the logical address before the data, the allocation correspondence table showing the correspondence between the physical address of the data after compression to be recorded on the disc and records on the disk, than expected compression ratio in said disk drive main body
When the actual compression rate becomes small, a special recording area for recording the compressed data is provided in advance on the disc only when the size of the compressed data is equal to or larger than the remaining data recording capacity. A disk drive device characterized in that 2. A disk drive apparatus according to claim 1, wherein the recorded contents of the allocation correspondence table is non-compressed data. 3. The disk drive device according to claim 2, wherein the special recording area is a replacement area. 4. When the disk is a rewritable disk and there is no access from the host computer, the allocation correspondence table is used to organize the recording positions of the compressed data already recorded on the disk. The disk drive device according to any one of claims 1 to 3 , wherein the disk drive device is performed as described above. 5. When the host computer issues a command for confirming the remaining data recording capacity on the disk, the apparent compression rate is reduced in response to the decrease in the unrecorded data recording capacity on the disk. The disk drive device according to any one of claims 1 to 4 , wherein the data recording capacity is reported to the host computer.