JP3620110B2 - File storage device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a file storage device using a magnetic material or a semiconductor memory and capable of writing and reading a plurality of variable length data at any time.
[0002]
[Prior art]
Conventionally, large capacity read / write external storage devices have been used for computer program storage and data storage. In these external storage devices, a characteristic of the storage medium is that the storage medium can be classified into a small capacity such as several hundred bytes to several kilobytes (hereinafter referred to as "sector" ”), Which is used as a read / write unit, and a plurality of sectors are concatenated and used to enable variable length data storage. Further, a configuration is generally used in which a file name is assigned to variable length data and a plurality of variable length files can be stored. As described above, in a large-capacity external storage device, a technique for storing a plurality of variable-length data by sector division has been established. However, as described above, a storage medium can be read and written as needed in units of sectors. A magnetic disk is the mainstream as a large-capacity storage medium that meets the specifications. However, due to recent improvements in the integration of non-volatile semiconductor memories, development of memory cards with a storage capacity of several tens of megabytes called flash ROM has progressed, making them smaller, lighter and more resistant to mechanical shock than magnetic disks. Because of this feature, it has become possible to consider using it as an external storage device. Taking advantage of the above features, these memory cards are being introduced as external storage devices for portable computers and industrial equipment with severe operating conditions.
[0003]
A conventional file storage device will be described below with reference to the drawings.
FIG. 6 is a block diagram showing a conventional file storage device 600. In FIG. 6, reference numeral 601 manages the use status of sectors in the data storage unit 602, which will be described later, and also manages variable length data by managing the size of each data, the head sector number, and the file name that is the identifier of each data. A plurality of file information management units 602, a data storage unit 602 that stores data divided into small sector sectors, and 603, an application described later when reading and writing to the data storage unit 602, which is a storage medium, is slow A cache unit 604 that temporarily stores a copy of the contents of the file information management unit 601 and the data storage unit 602 in a semiconductor memory with a short read / write response time in each stage in order to speed up the response time from the unit 606 to the read / write Is a sector necessary for creating a new file in response to an instruction from the application unit 606 described later. A file control unit 605 for acquiring, concatenating, data size, and storing a file name; after an application unit 606 described later instructs the file control unit 604 to create a new file, the data to be actually stored is transferred, A data transfer unit 606 to be written in the data storage unit 602 is an application unit on the main apparatus that instructs the file control unit 604 to create a new file.
[0004]
A method of using the file storage device configured as described above will be described.
[0005]
As a method of using the cache unit 603, in the case of writing, a write-through method in which data is written to the cache unit 603 and immediately written to the data storage unit 602, and writing is performed only in the cache unit 603, and write data is not updated for a certain period of time. There is a write back method for writing to the data storage unit 602. In the case of reading, there is a method of reading the content of the cache unit 603 instead of the content of the data storage unit 602 when the data of the sector designated to be read is stored in the cache unit 603. It is a common method. In the above write-through method, only the reading time is shortened, and in the write-back method, both the reading time and the writing time are shortened. In addition, when important data is stored in such a file storage device, by duplicating the file storage device and storing data simultaneously in two devices, even if one device fails, the other Methods are used to prevent data loss by using devices.
[0006]
[Problems to be solved by the invention]
However, in the conventional file storage device, the file name and data size are written to the file information management unit 601 on the storage medium during data writing, and the sector state is also changed. When the writing process cannot be continued due to the occurrence, data that has not been written is also created as a file. In addition, these data cannot be distinguished whether or not the writing is incomplete unless measures such as taking a checksum are taken, and in the case of means for taking the checksum, the configuration becomes complicated, resulting in high cost and large size. It was. In addition, since the file information management unit 601 is not duplicated in a single device, if a similar failure occurs during the update of the file information management unit 601 after data writing is complete, an inconsistency in the sector connection state occurs. In addition to the file being written, the management information of other files was destroyed. Further, when using the write back cache unit, writing from the cache unit to the file information management unit 601 is also delayed, which increases the risk of file destruction due to a power failure or the like. . Further, the method of duplicating the device itself is effective for the failure of the device itself, but has a problem that the cost is increased and the size is increased.
[0007]
The present invention solves the above-mentioned conventional problems, and provides a small and low-cost file storage device that does not create an incomplete file even if a power failure or a main device failure occurs during writing. With the goal.
[0008]
[Means for Solving the Problems]
In order to achieve this object, a file storage device and a writing method thereof according to the first invention of the present invention include :
A file storage device having a readable / writable storage medium composed of sectors each having a plurality of bytes as a unit, the file storing the file name, head sector number, sector connection order, and data size arranged on the storage medium and a data storage unit for storing the information management unit and the data, a cache unit that holds the same type of data and file information managing unit updates the contents of a file in the file information managing unit, the data between the data storage unit A data transfer unit that reads / writes the data, writes data in the data transfer unit to the data storage unit when a write request is received from the main unit, and stores data in the cache unit when a write completion is notified from the main unit The present invention relates to a file control apparatus and a method for writing the file control apparatus, wherein the file control apparatus writes to an information management unit .
[0010]
According to a second aspect of the present invention, there is provided a file storage device and a writing method therefor , comprising: a file storage device having a readable / writable storage medium comprising sectors each having a plurality of bytes as a unit, the file being arranged on the storage medium and a first data storage unit for storing a file information management unit and the data of the second to store the name and the top sector number and sector connecting order and data size, the first file information managing unit of the same type A cache unit that holds the data of the first file information management unit and updates the file contents of the first file information management unit, a data transfer unit that reads and writes data between the data storage unit, and first and second file information at startup file information detected errors data of another file information managing unit error-free if it detects an error in the file content to one of the management unit And a initial diagnosis unit for correcting are copied to processing section writes the data in the data transfer unit when requested to write from the main unit to the data storage unit, the cache unit when notified of the completion of the writing from the main unit Is written in the first information management unit, and an error is detected and corrected by the initial diagnosis unit at the time of activation.
[0011]
[Action]
With this configuration, the file control unit can write the data of the cache unit to the file information management unit when the data writing is completed, so no change is made to the file information management unit until the data writing is completed, If a power failure or main unit failure occurs during the process, an incomplete file will not be created. Further, the apparatus itself is not duplicated, and downsizing and cost reduction are achieved.
[0012]
If an error in the file contents is detected in either the first or second file information management unit, the data in the file information management unit without error is copied to the file information management unit in which the error is detected and corrected. As a result, it is possible to correct the file contents in which an error is detected using a complete file before or after the file is created, and a halfway file is not created. Further, even if one of the file information management units is destroyed, it can be corrected in the same manner by copying the content of the file that has not been destroyed. Furthermore, the apparatus itself is not duplicated, and downsizing and cost reduction are achieved.
[0013]
【Example】
(Example 1)
Hereinafter, a file storage device according to an embodiment of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a block diagram showing a file storage device 100 according to an embodiment of the present invention.
[0015]
In FIG. 1, 101 is a first file information management unit that manages data on the data storage unit 103, 102 is a second file information management unit that holds the same type of data as the first file information management unit 101, Reference numeral 104 denotes a semiconductor memory having a high read / write speed and holds the entire contents of the first file information management unit 101. Reference numeral 105 denotes a process when a file read / write is requested from the application unit 108 on the main apparatus. A file control unit 106 performs data reading / writing with the data storage unit 103 and reads / writes data designated by the application unit 108, and 107 detects and corrects file content errors when the file storage device 100 is started up. It is an initial diagnosis part. The first file information management unit 101, the second file information management unit 102, and the data storage unit 103 are arranged on a storage medium.
[0016]
A method of storing a plurality of variable length data in the file storage device configured as described above will be described. FIG. 2 is a data state diagram showing the first file information management unit 101, the second file information management unit 102, and the data storage unit 103. As in the conventional example, the data storage unit 103 is obtained by dividing a storage medium into small sections and assigning them. In this embodiment, the data storage unit 103 is composed of 12 sectors of 512 bytes per sector, and file names of file 1b and file 2b are assigned to two data having a data size of 200 bytes and 600 bytes, respectively. A case where data is stored in the data storage unit 103 will be described. As shown in FIG. 2, the first file information management unit 101 has a directory 1 and a file allocation table (FAT) 1a. The directory 1 has the data sizes of the files 1b and 2b in the areas 1101 and 201 and the data sizes in the areas 1102 and 202. 200, 600, and head sector numbers 211 and 212 of the area 1103. The second file information management unit 102 has a directory 2 and a file allocation table (FAT) 2a. The second file information management unit 102 will be described in the second embodiment. Since the file 1b has a data size of 200 bytes and fits within one sector (512 bytes), it is stored as the sector number 211 on the FAT 1a. However, since the file 2b has a data size of 600 bytes, a 512-byte sector is stored. Are required, the next sector number 213 is written in the sector 212 on the FAT 1a, and FF is written in the last sector 213 as the mark.
[0017]
In the file storage device 100 having such a configuration, an operation when the file 2b of FIG. 2 is newly written from the application unit of the main device to the file storage device will be described with reference to FIG. FIG. 3 is an operation procedure diagram for explaining the operation of the file storage device 100. 3, 101 is a first file information management unit, 103 is a data storage unit, 104 is a cache unit, 105 is a file control unit, 106 is a data transfer unit, and 108 is an application unit, which are the same as in FIG. Therefore, the same reference numerals are given and the description is omitted. First, the file control unit 105 that has received an open request instructing creation of a new file from the application unit 108 searches for an area for storing a new file in the directory area on the cache unit 104 (S1, S2), and an empty area. If there is, the file name designated by the application unit 108 is registered in the region 201 as shown in FIG. 2, “0” is registered in the region 202 as the initial value of the data size, and the application unit 108 is acknowledged. An open confirmation is returned (S3). After receiving the open confirmation, the application unit 108 issues a 200-byte write request to the data transfer unit 106 (S4, S5). The data transfer unit 106 searches for an empty sector 212 (see FIG. 2) necessary for storage, writes it in the first sector number area 203 of the directory 1 (S6), adds the file length 200 to the data size area 202, and is requested to write. 200 bytes of stored data are held (S7).
[0018]
Next, the application unit 108 makes a 200-byte write request again (S8). This is a total 400 bytes write request (accumulation size), but since this accumulation size does not exceed 512 bytes for one sector, it is accumulated in the data transfer unit 106 (S9, S10). Next, when receiving the third 200-byte write request, 512 bytes for one sector are written to the data storage unit 103 on the storage medium (S11). The remaining 88 bytes of the 200 bytes are held in the data transfer unit 106 (S12). In order to hold the 88 bytes, a new empty sector 213 (see FIG. 2) is searched for, and the empty sector 212 is stored. The sector number 213 is written (S13). Finally, when the file control unit 105 receives a close notification informing the completion of writing from the application unit 108, the remaining data of the data transfer unit 106 is written into the data storage unit 103 (S15) and the first file Data of the content held in the cache unit 104 is written into the information management unit 101 (S16).
[0019]
As described above, according to the present embodiment, the data of the cache unit 104, which is management information such as the file name and file length, is written to the first file information management unit 101 when data writing to the sector is completed. No changes are made to the contents of the first file information management unit 101 until the data writing is completed, and even if a power failure or a failure of the main unit occurs in the middle, there is no effect on the first file information management unit 101. Therefore, the first file information management unit 101 does not create an incomplete file. If a power failure or main device failure occurs in the middle, file creation will be started again.
[0020]
(Example 2)
The file storage device according to the second embodiment of the present invention will be described below. The file storage device according to this embodiment has the same configuration as that shown in FIG. In the first embodiment, the second file information management unit 102 is not used (see FIG. 3), but in the present embodiment, the second file information management unit 102 is used. That is, the file information management unit is duplicated into the first file information management unit 101 and the second file information management unit 102.
[0021]
First, data destruction that occurs when a power failure occurs during the file writing completion process in steps 15 and 16 of FIG. 3 will be described with reference to FIG. 4A is a data state diagram of the first file information management unit 101, and FIG. 4B is a data state diagram of the second file information management unit 102. 4A and 4B, 400 and 401 are directories, 402 to 404 are file allocation tables, and 405 to 414 are sectors.
[0022]
In FIG. 4A, the data writing of the file using the sectors 405, 406, 407, and 408 is completed, and the directory for the first file information management unit 101 is notified by the cache flush notification of the close notification in step 16 of FIG. If a power failure occurs when the writing of 400, 401 and FAT 402 is completed, sector 407 pointed to by sector 406 remains in the previous empty state, and this file remains disconnected at 406. In this state, after the power failure is restored and a new file is created and the sector 407 is used, the file indicated by the sector 406 and the newly created file simultaneously use the sector 407. Will occur. Further, as shown in FIG. 4B, the sector linkage order of the newly created file is arranged as sectors 413 and 414 after the sectors 411 and 412, and the sector 413 is updated. When a power outage occurs, the sector 410 points to an empty sector, which may cause the above-mentioned link crossing condition, and the two sectors 413 and 414 are not used for any file and are registered in the directory. Even if all existing files are deleted, they remain in use, so that there is a problem that the size of the usable data storage unit 103 is reduced. The present embodiment solves these problems.
[0023]
Next, the operation of the file storage device according to the present embodiment will be described with reference to FIG. 5A, 5B, and 5C are data state diagrams of the first and second file information management units 101 and 102. FIG. In this embodiment, the file information management unit is duplicated such as the first file information management unit 101 and the second file information management unit 102, and at the time of processing of the file close cache flush notification in step 16 of FIG. In addition, writing is sequentially performed like the directory 500 and the FAT 501 of the first file information management unit 101 and the directory 502 and the FAT 503 of the second file information management unit 102. For this reason, even if a power failure occurs during writing, the location where a failure has occurred is limited to one place, such as FAT 504 in FIG. In this case, after the power failure is restored, the initial diagnosis unit 107 checks the sector connection status of all the files in the first file information management unit 101 and the second file information management unit 102, and empty sectors are not used for the file. Is detected, the empty sector 504 is found, and the contents of the second file information management unit 102 are copied to the entire file of the first file information management unit 101, so that the state before the file is created Can be returned to. On the other hand, as shown in FIG. 5C, when a faulty part is found in the FAT 506 of the second file information management unit 102, the contents of the first file information management unit 101 that has been updated ( By copying the content of the corresponding FAT 506) to the second file information management unit 102, it is possible to reproduce the newly created file in a correctly linked state.
[0024]
As described above, according to the present embodiment, when an error in the file contents is detected in either the first file information management unit 101 or the second file information management unit 102, there is no error in the file information management unit. Since the file data was copied to the file information management unit that detected the error and corrected, the file contents that detected the error can be corrected using the complete file before or after the file was created. Never created. Further, even if one of the file information management units is destroyed, it can be corrected in the same manner by copying the content of the file that has not been destroyed.
[0025]
【The invention's effect】
As described above, the present invention includes a file information management unit that stores a file name, a head sector number, a sector connection order, and a data size, a cache unit that holds the same type of data as the file information management unit, and a cache unit. By providing a file control unit for controlling, the data in the cache unit can be written into the file information management unit when the data writing is completed, so there is no content in the file information management unit until the data writing is completed. A file that is not changed and does not affect the file information management unit even if a power failure or main unit failure occurs in the middle, so an incomplete file is not created in the file information management unit A storage device can be realized. Also, since the device itself is not duplicated, a file storage device that can be reduced in size and cost can be realized.
[0026]
In addition, the file control unit writes the data in the cache unit to the file information management unit when the writing of data to the sector is completed, so that even if a power failure or failure of the main unit occurs before the data writing is completed, the file information management The file information management unit can realize a file storage device in which an incomplete file is not created.
[0027]
Furthermore, the first and second file information management units that store the file name, the first sector number, the sector connection order, and the data size, and the same type of data as the first file information management unit are held, and the data writing is completed If an error in the file content is detected in either the cache unit that sequentially updates the contents of the first and second file information management units or the first and second file information management units at startup By providing an initial diagnosis unit that copies and corrects the data of the missing file information management unit to the file information management unit that detected the error, it is possible to complete the file before file creation, that is, before file update, or after file creation, that is, after file update. File storage device that does not create a half-finished file because it can correct the contents of the file that detected the error using the file. It can be realized. Also, since the device itself is not duplicated, a file storage device that can be reduced in size and cost can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a file storage device according to an embodiment of the present invention. FIG. 2 is a data state diagram illustrating a first file information management unit, a second file information management unit, and a data storage unit. FIG. 4A is a data state diagram of the first file information management unit, and FIG. 4B is a data state diagram of the second file information management unit. 5 (a), (b), and (c) are data state diagrams of the first and second file information management units. FIG. 6 is a block diagram showing a conventional file storage device.
DESCRIPTION OF SYMBOLS 100 File storage device 101 1st file information management part 102 2nd file information management part 103 Data storage part 104 Cache part 105 File control part 106 Data transfer part 107 Initial diagnosis part 108 Application part

Claims (4)

A method of writing a file storage device having a readable / writable storage medium composed of sectors each having a plurality of bytes as a unit,
A file information management unit for storing a file name, a head sector number, a sector connection order, and a data size, and a data storage unit for storing data, which are arranged on the storage medium;
Includes a cache unit to update the contents of a file in the file information managing unit retains the file information managing unit of the same type of data, and a data transfer unit for reading data from and writing data to and from the data storage unit ,
Write request step for writing data in the data transfer unit to the data storage unit when writing is requested from the main unit, and writing the data in the cache unit to the information management unit when notified of completion of writing from the main unit A file storage device writing method comprising: a close notification step. A method of writing a file storage device having a readable / writable storage medium composed of sectors each having a plurality of bytes as a unit,
It has the disposed on the storage medium, the first and the file information managing section and the second storing the file name and the start sector number and the sector coupling order and data size, a data storage unit for storing data ,
A cache unit to update the contents of a file in the first file information managing unit retains the same type of data and the first file information management unit,
A data transfer unit that reads and writes data to and from the data storage unit;
In the file information managing unit which detects an error of the data of other file information managing unit error-free if it detects an error in the file content to one of said first and said second file information management unit at start An initial diagnosis unit that copies and corrects ,
A write request step for writing data of the data transfer unit to the data storage unit when a write request is made from the main unit; and a first information management of the data of the cache unit when a completion of writing is notified from the main unit A file storage device writing method, comprising: a close notification step for writing to a storage unit; and an initial diagnosis step for performing error detection and correction by the initial diagnosis unit at startup. A file storage device having a readable / writable storage medium composed of sectors each having a plurality of bytes as a unit,
A file information management unit for storing a file name, a head sector number, a sector connection order, and a data size, and a data storage unit for storing data, which are arranged on the storage medium;
Includes a cache unit to update the contents of a file in the file information managing unit retains the file information managing unit of the same type of data, and a data transfer unit for reading data from and writing data to and from the data storage unit ,
The data of the data transfer unit is written into the data storage unit when writing is requested from the main device, and the data of the cache unit is written into the information management unit when notified of completion of writing from the main device. File storage device. A file storage device having a readable / writable storage medium composed of sectors each having a plurality of bytes as a unit,
It has the disposed on the storage medium, the first and the file information managing section and the second storing the file name and the start sector number and the sector coupling order and data size, a data storage unit for storing data ,
A cache unit to update the contents of a file in the first file information managing unit retains the same type of data and the first file information management unit,
A data transfer unit that reads and writes data to and from the data storage unit;
In the file information managing unit which detects an error of the data of other file information managing unit error-free if it detects an error in the file content to one of said first and said second file information management unit at start An initial diagnosis unit that copies and corrects ,
Inclusive can write the data of the data transfer unit to the data storage unit when requested to write from the main unit, the first information management section data of the cache unit when notified of the completion of the writing from the main unit A file storage device wherein writing and error detection and correction are performed by the initial diagnosis unit at startup .

Images