JP2006133923A - Data recording/reproducing device, recording/reproducing method, program and data recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restore data even when a FAT or a directory is destroyed when substance of data is left in a data recording medium. <P>SOLUTION: Each page of data recorded in a user data area 2 comprises a data part 11 and a redundant part 12, and link information 14 is recorded in the redundant part 12. The link information is a logical address number of a block written just before writing the block. When the link information 14 is recorded, substance data are restored by tracing the link information 14 sequentially from behind, when the substance data of a file are left even if a directory table 3 and/or a FAT chain 4 cannot be read. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data recording / reproducing apparatus, a recording / reproducing method, a program, and a data recording medium applied to, for example, a NAND flash memory.

For digital still cameras, etc., MS-DOS (Microsoft Disc Operating System) (
A registered trademark compatible FAT (File Allocation Table) file system is used.
For example, Patent Document 1 below describes a data storage device that applies a FAT file system to a memory card as a nonvolatile memory.

JP 2003-308241 A

  If the user accidentally deletes an image, formats the media, etc., or if the management area such as FAT is damaged due to an erroneous operation, etc., the image data remains in the media, but link information for the data remains. Since it is lost, the data cannot be accessed.

In this state, it may be possible to restore the image data using the application software of the personal computer. When image data is continuously recorded on the medium, the image can be easily restored by searching for a JPEG (Joint Photographic Experts Group) marker. However, when the data arrangement is discontinuous as a result of repeated recording and deletion, it is difficult to restore the image.

  Therefore, the object of the present invention is to make the link information remain until the data body is erased or overwritten, and it is possible to easily restore the data even if the data is discontinuous using the link information. A data recording / reproducing apparatus, a recording / reproducing method, a program, and a data recording medium are provided.

In order to solve the above-described problem, according to a first aspect of the present invention, recorded data is collectively erased in units of blocks having a predetermined amount of data, and a redundant portion having a predetermined length is provided for each data portion having a predetermined length. In a data recording / reproducing apparatus including a nonvolatile memory in which data is recorded in data units having:
In this data recording / reproducing apparatus, when data is recorded in the data part, link information that can identify the recording order of the data is recorded in the redundant part of the data part.

According to the second aspect of the present invention, the recorded data is erased in batches in units of a predetermined amount of data, and data is recorded in units of data having a predetermined length of redundant portion for each predetermined length of data portion. In a data recording / reproducing method using a non-volatile memory,
This is a data recording / reproducing method for recording link information capable of identifying the recording order of data in the redundant portion of the data portion when data is recorded in the data portion.

In the third aspect of the present invention, the recorded data is erased in batches of a predetermined amount of data, and data is recorded in units of data having a predetermined length of redundant portion for each predetermined length of data portion. In a program for causing a computer to execute a data recording / reproducing method using a non-volatile memory
This is a data recording / reproducing method program for recording link information capable of identifying the recording order of data in the redundant portion of the data portion when data is recorded in the data portion.

According to a fourth aspect of the present invention, the recorded data is erased in batches of a predetermined amount of data and data is recorded in units of data having a predetermined length of redundant portion for each predetermined length of data portion. A non-volatile memory, a buffer memory, a control unit, and an interface for connection to the host side,
When the control unit records data in the nonvolatile memory, the data recording medium records link information that can identify the recording order of the data in the redundant portion of the data unit.

  According to the present invention, by recording link information in the redundant part of the flash memory, even when data is deleted by mistake, even discontinuous data can be recovered. Therefore, more data can be recovered at high speed. In the present invention, since the data and the link information are recorded in the same recording / reproduction unit, as long as valid data remains, the link information also remains, compared with a method of managing the link information in another file or the like. , Data can be reliably revived.

  Prior to description of one embodiment of the present invention, conventional problems will be described with reference to FIGS. The present invention is applied to a NAND flash memory as a storage medium.

  In the MS-DOS compatible format, data reading / writing units for media are called cylinders, heads, and sectors. A cluster having a size that is a multiple of the sector size is defined as a unit for managing data recorded therein.

  In the logical format applied to the NAND flash memory, the storage area is divided into a plurality of blocks which are units of data erasure. A block is a unit for erasing data, and at the same time is a minimum unit for file management. That is, a file is stored in one or a plurality of blocks, and a plurality of files are not mixed in one block. Furthermore, one block consists of a plurality of pages. Data writing / reading to / from the flash memory is performed in units of pages. For example, the size of one page is 512 bytes.

In MS-DOS, MBR (Master Boot Record), PBR (Partition Boot Record), FAT, and root directory entry are defined as file management data. As an example, one partition is formed for the flash memory.

  The MBR is arranged at the head of the user area. Information of each partition (for example, start LBA sector number and size) is recorded in the MBR.

  The PBR is arranged in the head sector of each partition. The sector in which the PBR is recorded is described in the start LBA sector number in the MBR. The LBA sector number is a number uniquely assigned to each sector in the valid block (or a substitute block of the valid block). LBA sector numbers are assigned in ascending order from the top of a block having a logical block number of 0.

  The FAT is recorded over a plurality of sectors from the sector following the PBR. The FAT represents a connection state of files handled in the user area in cluster units.

  Data recorded on the medium is managed in cluster units. When one file is composed of a plurality of clusters, it is necessary to read the next cluster after reading one cluster. However, the next cluster is not always recorded at physically continuous positions on the flash memory. The FAT is information indicating which cluster is a cluster following a certain cluster. The subsequent relationship of the clusters indicated by the FAT is referred to as a FAT chain.

  All clusters existing on the medium are assigned cluster numbers starting from cluster number 0002. A cluster number is uniquely assigned to each storage area in the FAT. Each storage area stores the next cluster number connected to the cluster of the assigned cluster number. Therefore, the cluster number of the next cluster can be known by referring to the cluster number stored in the storage area to which the cluster is allocated.

  Two FATs are recorded for backup. The physical data size of one FAT is constant because the number of clusters in the flash memory does not change.

  In the root directory entry, entries of files and subdirectories arranged in the root directory are described. The root directory entry is recorded from the next sector following the last sector in which the FAT is recorded. The data size of the root directory entry is constant. The first cluster (cluster number “02”) in the user area starts from the next sector following the file management data described above.

  FIG. 1 is an example of data for explaining when data is recorded in the flash memory according to the FAT file system. In the following description, processing in units of blocks and pages will be described instead of blocks and sectors.

  In FIG. 1, reference numeral 1 represents file management data, and reference numeral 2 represents an area of user data. In the user data area 2, “logic” means a logical address. For example, “logic 02” indicates that the logical block address number is 2. As shown in FIG. 1, the start position of the FAT chain 4 is described in the directory table 3. As items in the directory table 3, “Test1.dat 0002” and “Test2.dat 0005” are shown. Test1.dat and Test2.dat are file names, respectively, and 0002 and 0005 indicate the first block numbers of the files.

  As indicated by the data entity of the file indicated by reference numeral 5, the file “Test1.dat” is continuously recorded from block 02 of block number 0002 to block 04 of block number 0004. Skipped and recorded continuously in blocks 06 and 07 of block numbers 0006 and 0007. The file “Test2.dat” is recorded only in block 05 of block number 0005.

When data is recorded in this way, the subsequent block numbers are recorded in the FAT chain 4 recorded in the FAT storage area to which the block numbers 0002 to 0009 are assigned, as shown in the figure. Is done. Here, ffff means that there is no following block, that is, the last block. In the case of the file “Test1.dat”, 0003,0004,0006, ffff (the end of the file of Test2.dat), 0007, ffff are recorded in the storage areas allocated to block numbers 0002 to 0007, respectively. The

As shown in FIG. 1, when data is recorded and the file “Test1.dat” is deleted, the file “Test1.dat” in the directory table 3 as shown in FIG. Delete mark (indicated by ×) and “Test1.dat” in FAT
The chain information for the file is cleared. In this case, the data entity 5 is not erased. Since the file “Test2.dat” has not been deleted, the value of the storage area assigned to the block number 0005 remains ffff.

  FIG. 3 shows a case where the flash memory is quick formatted. In the quick format, the information in the directory table 3 and the FAT chain 4 are cleared, but the data entity 5 is not erased.

  FIG. 4 shows a case where the directory 3 and / or the FAT 4 is destroyed due to some malfunction. In this case, the data cannot be accessed, but the data entity 5 remains on the flash memory.

  FIG. 5 shows a case where the flash memory is fully formatted (means not quick format). In this case, since the entire memory is erased, the information in the directory table 3 and the FAT chain 4 are cleared, and the data entity is also erased. That is, all 0 or all ff data is overwritten on the data. In this case, data restoration is physically impossible.

  As shown in FIG. 2, FIG. 3 and FIG. 4, data cannot be accessed by a normal method, but if the data entity 5 remains in the flash memory, the data has been restored by some method. ,It is considered.

  In the JPEG file format, the file is delimited by a 2-byte marker code. An SOI (Start Of Image) marker code (ffd8) (hexadecimal display) is placed at the beginning of the file, and an EOI (End Of Image) marker code (ffd9) (hexadecimal display) is placed at the end of the file. Is arranged. Therefore, when the data to be revived is JPEG, the image data can be revived by searching the data area and cutting out the substance of data from SOI to EOI to form one file.

  In this method, as shown in FIG. 6, when the FAT chain of the file “Test1.jpg” is continuous from block numbers 0002 to 0007, the data 6 can be restored correctly. Since the end position of the block having the block number 0007 does not coincide with the end position of the EOI, there is a part of the dummy area indicated by hatching.

  However, as shown in FIG. 7, when the data 6 of the JPEG file is recorded in consecutive blocks from block numbers 0002 to 0004, and the blocks of block number 0005 are skipped and recorded in block numbers 0006 and 0007 However, even if the method of cutting out SOI to EOI and making it into one file is used, the JPEG file cannot be accessed correctly. That is, in the example shown in FIG. 7, since irrelevant data (“Test2.dat”) recorded in the block with the block number 0005 is included in the extracted data, the JPEG file can be correctly extracted. Can not. In this case, it is necessary to guess the correct FAT chain by trial and error for each block number so as to obtain correct image data.

  In the present invention, by storing a hint for determining a correct FAT chain, the number of trial and error is greatly reduced, and more data is restored at high speed. If the hint data for reinstating the FAT chain is recorded in a separate management area from the file data, the file data and the hint data may not be consistent. The present invention records information (hereinafter referred to as link information as appropriate) that serves as a hint for restoring the FAT chain in the same data unit as the file data.

  In one embodiment of the present invention, link information is recorded in a redundant portion added to each page. In a NAND flash memory used as an external storage medium such as a memory card or a built-in flash memory, as shown in FIG. 8, a redundant portion 12 (16 bytes) together with a data portion 11 (512 bytes) for one page. Areas are defined.

  The redundant part 12 is information for managing the block in which the redundant part is stored. The redundancy unit 12 includes a 2-byte flag including a flag indicating whether or not a block can be used, a 2-byte logical address, a 7-byte free area 13, and 3-byte data (512-byte data). Error correction code (ECC) parity code for 2-byte and error correction code (ECC) parity code for 2-byte redundant part. However, the flag is not subject to error correction coding for the redundant portion.

In one embodiment of the present invention, as shown in FIG. 9, the link information 14 is recorded using 2 bytes in the 7-byte free area 13. Therefore, the empty area has a size of 5 bytes as indicated by 13 '. The link information 14 is error correction encoded together with the logical address. Since the link information of about 2 bytes is recorded, the increase in cost and processing time can be reduced.

  The link information 14 is the logical address number of the block written immediately before writing this block. By recording such link information 14, it is possible to follow the order in which data was written later. The data actually recorded as the link information 14 is not limited to the logical address number of the immediately preceding block, but may be any of the immediately preceding physical address number, the immediately following logical address number, and the immediately following physical address number. Furthermore, a unique sequential number determined in the order in which data is recorded in the medium may be used as the link information 14.

  A method for using link information will be described with reference to FIG. Here, for the sake of simplicity, it is assumed that a relationship of block number = logical address = physical address exists. As described above, each page of data recorded in the user data area 2 includes the data part 11 and the redundant part 12, and the link information 14 is recorded in the redundant part 12. One block includes a predetermined number of pages, but the link information of the same block is the same information.

  When data is recorded in the same manner as shown in FIG. 1, the link information 14 recorded on each page of each block number is as shown in FIG. Here, the link information 14 is the logical address number of the block written immediately before writing this block. In the blocks of block numbers 08 and 09, since no data is written, the 2-byte link information is set to an initial value (0000).

  The link information 14 of block number 07 is the block number (0006) of the block written immediately before, and the link information 14 of block number 06 is the block number (0004) of the block written immediately before. In the link information 14 with the block number 05, since one file data is written in one block, there is no block written immediately before, so the link information 14 is (0000). The link information 14 with the block number 04 is the block number (0003) of the block written immediately before, and the link information 14 with the block number 03 is the block number (0002) of the block written immediately before.

  As described above, when the link information 14 is recorded, even if the directory table 3 and / or the FAT chain 4 cannot be read, the link information 14 is traced in order from the rear if the substance data of the file remains. The actual data can be restored. The link information 14 may be the block number to be written next instead of the block number written immediately before. However, the method of remembering the block number recorded immediately before and recording it together with the next data can reduce the amount of change from the existing control processing.

FIG. 11 is an outline of the configuration of a digital camera to which the present invention can be applied. Reference numeral 21 indicates a CPU (Central Processing Unit), and reference numeral 22 is a CPU bus. C
A ROM 23, a RAM 24, a photographing unit 25 and an image processing unit 26 are connected to the PU bus 22.

  The ROM 23 stores data such as programs. The RAM 24 is a work memory used by the CPU 21 for processing. The photographing unit 25 is configured by an imaging element such as a CCD (Charge Coupled Device), and digitized photographing data is output from the photographing unit 25. The image data is subjected to JPEG compression processing by the image processing unit 26.

  An input unit 32, an output unit 33, a communication unit 34, a NAND flash memory 35, and a memory card interface 36 are connected to the CPU bus 22 via an input / output interface unit 31.

The input unit 32 is a plurality of keys such as a shutter button. The output unit 33 is a display unit such as an LCD (Liquid Crystal Display). The communication unit 34 is a part that communicates with a personal computer, for example, a USB. The NAND flash memory 35 is built in the digital camera. A removable memory card 37 is connected via the memory card interface 36. The memory card 37 has a NAND flash memory and a control unit.

  An image photographed by the photographing unit 25 is displayed on the output unit 33. When the shutter button of the input unit 32 is pressed, an image is captured by the photographing unit 25, compression processing by JPEG is performed by the image processing unit 26, and JPEG data is applied to one or both of the NAND flash memory 35 and the memory card 37. To be recorded.

  FIG. 12 shows an example of the configuration of the memory card 37. The memory card 37 includes a flash memory 41, a RAM 42 for buffering write data and read data, a controller 43 that controls each part of the memory card 37, and an interface 44. The CPU 21 (having a position as a host computer) of the digital camera directly controls the memory card 37 via the interface 44 and the memory card interface 36. Access to the flash memory 41 is physical block access. As described above with respect to the built-in NAND flash memory 35 and memory card 37, the CPU 21 writes and reads link information to and from the redundant portion of each page.

  FIG. 13 shows another example of the configuration of the memory card 37. The difference from the configuration example of FIG. 12 is that a CPU 44 is provided instead of the controller 43. The CPU 44 writes and reads link information to and from the redundant part of each page. The CPU 21 as the host computer performs logical block access to the memory card 37. Therefore, the CPU 21 on the host side does not have to write and read link information, and no additional processing is required for the existing processing of the CPU 21.

  Next, processing at the time of data recording will be described with reference to FIG. The flowchart shown in FIG. 14 shows the overall flow of processing when data is recorded, and this processing can be commonly applied to both the built-in flash memory 35 and the removable memory card 37. When the CPU 21 directly controls the address as in the flash memory 35 or the memory card 37 shown in FIG. 12, the processing at the time of data recording shown in FIG.

  As shown in FIG. 10, description will be given with reference to an example of recording data and link information. As in the case of FIG. 10, for the sake of simplicity, it is assumed that a relationship of block number = logical address = physical address exists. In the first step S1, an empty cluster A is calculated from the FAT. For example, an empty cluster 0002 is required. In step S2, a logical address B such as 0002 is calculated from the cluster number 0002.

  In step S3, data and link information are recorded for logical address B. The process of step S3 will be described in detail later with reference to FIG.

  After the recording process, the chain of cluster A, for example, 0002 is updated in the FAT. Specifically, ffff is written in 0002. Then, it is determined in step S5 whether or not the recording of data for the file size has been completed. If it is determined that the process has not been completed, the process returns to step S1, and the processes from step S2 to step S4 are repeated. If it is determined that the recording of the data for the file size has been completed, the directory and FAT data are recorded in step S6, and the recording process ends.

  More specifically, the data recording process S3 in FIG. 14 is performed as shown in FIG. As an example, a case where data is recorded at the logical address 0002 and the second data recording process S3 is performed will be described. First, in step S31, an unused physical block C, for example, 0003 is calculated. In step S32, data is recorded for the physical block C. In step S33, the logical address B, for example, 0003 is recorded in the redundant portion of each page of the physical block C.

  In step S34, link information X is recorded in the redundant portion of each page of physical block C. The address of the block recorded immediately before, for example, 0002 is recorded as link information X in the redundant part. In step S35, the address 0003 of the physical block C is set to X. As described above, the link information X may be either a physical address or a logical address, or a serial number. Also, as shown in the flowchart of FIG. 16, in step S41 of the initialization process at power-on, an initial value 0 is set as the link information X.

  In step S36, the logical-physical conversion table (referred to as a logical / physical table) is updated. The logical / physical table is stored in the work RAM 24 of the CPU 21.

  As shown in FIG. 10, the flow of processing when data in the image in the RAM 42 is written in, for example, the block number 02, 03, 04, 06, 07 of the flash memory under the control of the CPU 21 is shown below.

  When writing data to block number 02, since there is no block written immediately before, 0000 is written simultaneously with the data as link information.

  Subsequently, when data is written to the block number 03, 0002 which is the block number written immediately before as link information is written simultaneously with the data.

  Subsequently, when data is written to the block number 04, 0003, which is the block number written immediately before as link information, is written simultaneously with the data.

  Subsequently, when data is written to the block number 06, 0004, which is the block number written immediately before, is written simultaneously with the data as link information.

  Subsequently, when data is written to the block number 07, 0006, which is the block number written immediately before, is written as link information at the same time as the data.

  As shown in FIG. 13, in the case of a memory card having a CPU 44, as described above, the CPU 44 controls the process of recording data, and automatically records link information inside the memory card. This link information is usually not visible from the host side. Therefore, the link information can be used by simultaneously reading the data and the link information of the redundant portion by using a special command (for example, ReadLong) at the time of data restoration that requires the link information.

  If the directory or FAT chain is disabled while data remains, the data is restored using a personal computer. For example, JPEG file restoration processing will be described with reference to FIG.

  First, data and redundant parts are read from the flash memory in the order of logical addresses. For the data read into the RAM of the personal computer, the SOI marker code (ffd8) (hexadecimal display) of the JPEG file 6 is searched from the beginning of the logical address.

  If the SOI marker code can be found, the physical address or the logical address is 0002, and the link information there is 0000. When a block in which 0002 is recorded as link information is searched, a block with block number 03 can be found. The block having the block number 03 as the link information is the block having the block number 04. The block having the block number 04 as link information is the block having the block number 06. The block having the block number 06 as the link information is the block having the block number 07. Since the EOI marker code (ffd9) (hexadecimal display) is recorded in the block number 07, the block number 07 is the end of the file.

  When an EOI marker code is found, data from SOI to EOI is cut out and stored as image data, and the validity of the data is confirmed. In this way, the JPEG file 6 can be restored.

  Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the present invention can be applied not only to a NAND flash memory but also to a nonvolatile memory such as an AND flash memory in which a redundant portion exists during data recording. The present invention is not limited to a digital camera, and can also be applied to recording and reproduction of digital data such as moving image data and music data.

It is a basic diagram used for description when data is recorded on the FAT file system to which the present invention can be applied. It is a basic diagram for demonstrating the case where data are deleted in a FAT file system. It is a basic diagram for demonstrating the case where a medium is quick-formatted. It is a basic diagram for demonstrating the case where a directory or FAT becomes unreadable in a FAT file system. It is a basic diagram for demonstrating the case where a medium is fully formatted. It is an approximate line figure for explaining restoration of data when image data is recorded continuously. It is a basic diagram for demonstrating that data cannot be restored | restored when image data are recorded discontinuously. 2 is a schematic diagram illustrating a data configuration of a NAND flash memory. FIG. It is a basic diagram which shows the structure which recorded link information in the redundant part in the data structure of NAND flash memory. It is a basic diagram for demonstrating the usage method of link information. 1 is a block diagram illustrating a configuration example of a data processing system to which the present invention can be applied, for example, a digital camera. It is a block diagram which shows the structure of an example of the memory card which can apply this invention. It is a block diagram which shows the structure of the other example of the memory card which can apply this invention. It is a flowchart which shows the flow of the process at the time of the data recording in one Embodiment of this invention. It is a flowchart which shows the flow of a process at the time of the data recording in one Embodiment of this invention in detail. It is a flowchart which shows the flow of the initialization process at the time of the power-on in one Embodiment of this invention. It is a basic diagram for demonstrating the repair process of the broken media in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 File management data 2 User data area 3 Directory table 4 FAT chain 5 Recorded data 6 JPEG file 11 Data part 12 Redundant part 14 Link information 21 CPU
25 Imaging unit 35 Built-in NAND flash memory 37 Removable memory card 43 Controller 44 in the memory card CPU 44 in the memory card

Claims (7)

Data recording / reproduction comprising a nonvolatile memory in which recorded data is erased in batches of a predetermined amount of data, and data is recorded in units of data each having a predetermined length of redundant portion for each predetermined length of data portion In the device
A data recording / reproducing apparatus configured to record link information capable of identifying a recording order of data in the redundant portion of the data portion when data is recorded in the data portion. The data recording / reproducing apparatus according to claim 1,
The non-volatile memory is included in an external recording medium accessed by a host computer,
A data recording / reproducing apparatus for recording link information in the data recording order in a redundant portion of the nonvolatile memory by the host computer. The data recording / reproducing apparatus according to claim 1,
The non-volatile memory is included in an external recording medium accessed by a host computer,
A data recording / reproducing apparatus for recording link information in a data recording order in a redundant portion of the nonvolatile memory inside the external recording medium. The data recording / reproducing apparatus according to claim 1,
The link information is the logical address of the data unit recorded immediately before, the physical address of the data unit recorded immediately before, the logical address of the data unit recorded immediately after, the physical address of the data unit recorded immediately after A data recording / reproducing apparatus which is one of unique sequential numbers determined in the order in which addresses and data are recorded. Data recording using a nonvolatile memory in which recorded data is erased in batches of a predetermined amount of data, and data is recorded in units of data having a redundant portion of a predetermined length for each data portion of a predetermined length In the playback method,
A data recording / reproducing method for recording link information capable of identifying the recording order of data in the redundant portion of the data portion when data is recorded in the data portion. Data recording using a nonvolatile memory in which recorded data is erased in batches of a predetermined amount of data, and data is recorded in units of data having a redundant portion of a predetermined length for each data portion of a predetermined length In a program for causing a computer to execute a playback method,
A program for a data recording / reproducing method for recording link information capable of identifying the recording order of data in the redundant portion of the data portion when data is recorded in the data portion. Non-volatile memory in which recorded data is collectively erased in units of blocks having a predetermined amount of data, and data is recorded in units of data having a redundant portion of a predetermined length for each data portion of a predetermined length, and a buffer memory And a control unit and an interface for connection to the host side,
A data recording medium for recording link information capable of identifying the recording order of data in the redundant portion of the data portion when the control portion records data in the nonvolatile memory.

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