JP2010182160A - Memory access device, nonvolatile storage device, nonvolatile storage system, memory access method, program and integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein, when a memory controller of a nonvolatile storage device does not support refreshing, a data holding period of the nonvolatile storage device cannot be extended as compared to a data holding period of a flash memory single body. <P>SOLUTION: In this memory access device 102 of a nonvolatile storage system 101, because a refresh control part can perform a reading/writing instruction of data of the nonvolatile storage device 103 by the file, refresh processing can be executed by the file defined by a prescribed file system. Accordingly, even if the memory controller 108 of the nonvolatile storage device 103 does not have a refresh function, the data holding period can be lengthened (extended) as compared to the data holding period of a nonvolatile memory 109 single body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a file system for managing a file recorded in a nonvolatile storage device such as a semiconductor memory card, SSD (Solid State Drive) having a rewritable nonvolatile memory such as a flash memory as a data storage medium, and a file system The present invention relates to a memory access device that has a data management function according to the above, and that writes to and reads from a nonvolatile storage device, and further includes a memory access device and a nonvolatile storage device.

Nonvolatile storage devices having a rewritable nonvolatile memory such as a flash memory are widely used mainly for semiconductor memory cards and SSDs, and such nonvolatile storage devices and digital cameras, personal computers, etc. The demand for combined non-volatile storage systems is increasing.
In general, a memory card or an SSD includes a flash memory that stores data and a memory controller that controls the flash memory. The memory controller is a device that controls reading / writing of data from / to a flash memory in accordance with a reading / writing instruction from an access device such as a digital camera. Usually, flash memory requires control such as defect management (defect control), wear leveling (leveling of the number of rewrites), error correction processing by ECC, and the like, and these controls are performed by the memory controller. A typical flash memory is a NAND flash memory.

In recent years, flash memory is problematic because the data retention period tends to be shortened due to miniaturization of the semiconductor manufacturing process and the increase in the number of memory cells.
For this problem, for example, there is a method disclosed in Patent Document 1. According to this method, the data retention period of the nonvolatile storage device is flashed by performing a “refresh” in which the data recorded in the flash memory is read from the flash memory for each recording unit of the flash memory and then written to the flash memory again. It can be extended from the data retention period of a single memory.
JP-A-8-147888

However, in the above conventional method, the memory controller included in the nonvolatile storage device needs to support refresh. When the memory controller does not support refresh, the data holding period is set to be longer than the data holding period of the nonvolatile memory alone. It cannot be extended.
In the conventional method, the nonvolatile storage device needs to have a clock or the nonvolatile storage device needs to acquire time information from the memory access device for refresh time management.
In the conventional method, when refresh is performed based on time information, it is necessary to record the write time (time information) for each recording unit of the nonvolatile storage device.
In the conventional method, when the refresh execution function for the nonvolatile memory is realized, the nonvolatile storage device is provided with the refresh execution function for the nonvolatile memory even if data is already stored in the nonvolatile memory. It is necessary to replace it with a sex memory device.

In addition, data to be recorded in the nonvolatile storage device is normally managed as a file by the file system. However, in the conventional method, a file to be refreshed is selected based on the importance of the file to be recorded in the nonvolatile storage device. Can not do it.
In view of the above problems, the present invention allows the memory access device to perform refresh in units of files, so that even if the memory controller of the nonvolatile storage device does not support refresh, the data retention period of the nonvolatile memory alone It is an object of the present invention to provide a memory access device, a nonvolatile storage device, a nonvolatile storage system, a memory access method, a program, and an integrated circuit that can be made longer than a data retention period.
Further, according to the present invention, it is not necessary for the nonvolatile storage device to have a clock for refresh time management, and it is not necessary for the nonvolatile storage device to acquire time information from the memory access device.

Further, according to the present invention, when performing refresh by time management, if the file system shares the file creation date and time with the write time used for refresh, it is not necessary to add a new write time for refresh.
In addition, in such a case, it is possible to introduce refresh to a nonvolatile memory in which data is already stored simply by installing the file system of the present invention in a memory access device and replacing the existing file system. It is possible and there is no need to replace the non-volatile storage device.
Furthermore, an object of the present invention is to perform refresh based on the importance of a file by giving importance information to the file.

A first invention is a memory access device for writing / reading data to / from a nonvolatile storage device including a nonvolatile memory, and includes a refresh control unit and a file management unit.
The refresh control unit, for a file recorded in the nonvolatile storage device managed by the file system, instructs to read data constituting only the file, and to write to the nonvolatile storage device without changing the read data. The refresh process is instructed. In writing data for the refresh process, the file management unit writes data constituting the file to the nonvolatile storage device, and also writes related information managed by the file system regarding the data.
In this memory access device, the refresh control unit, for the file recorded in the nonvolatile storage device managed by the file system, reads the data that constitutes only the file, and the read data to the nonvolatile storage device. The refresh process is instructed by instructing to write without changing.

As a result, it is possible to instruct reading / writing of data on the nonvolatile storage device in units of files, so that refresh processing can be executed in units of files defined in a predetermined file system. The “file-based refresh process” is a concept that includes a refresh process that is executed on a part of data constituting a file. For example, a refresh process performed on a part of the data constituting the file may be performed on a file having a large file size, and the refresh process in this case is also included in the concept of “file unit refresh process”. It is.
In addition, “related information managed by the file system regarding data constituting a file” means information on the location of the storage area (for example, FAT) in the logical storage area managed by the file system and the data. This means information used in addition to the file data when the file system manages the file, such as various information of bibliographic items such as file write time, update time, access time, and file size (for example, Directory Entry).

2nd invention is 1st invention, selects the file used as the object of a refresh process based on the additional information of the file currently recorded on the non-volatile memory | storage device, File identification information of this selected file Is further provided with a file selection unit that notifies the refresh control unit of the above. The refresh control unit instructs a refresh process for the file specified by the file identification information notified from the file selection unit. The file management unit further writes additional information to the nonvolatile storage device.
As a result, a file to be refreshed can be selected based on the file additional information.
Note that “additional information of a file” includes various types of information used as a judgment material when selecting a target file or judging whether or not to refresh when refreshing file data or system information data. Information. This information includes, for example, the recording time when the file was recorded immediately before, information indicating the importance of the file, a flag intended not to be refreshed, the number of times the refresh was performed, and the like. These pieces of information may be provided exclusively, or may use various information of files managed by the file system.

A third invention is a memory access device for writing / reading data to / from a nonvolatile storage device including a nonvolatile memory, and includes a refresh control unit, a file selection unit, and a file management unit.
The refresh control unit instructs the refresh process by giving an instruction to read the data constituting the system information recorded in the nonvolatile storage device and then writing the read data to the nonvolatile storage device. The file selection unit notifies the refresh control unit of the refresh process of the system information based on the additional information of the system information recorded in the nonvolatile storage device. In writing data for the refresh process, the file management unit writes the data constituting the system information and the additional information of the system information to the nonvolatile storage device.

Thereby, system information refresh processing can be performed.
The “system information” means information other than information for managing data by the file system. For example, information such as an MBR (Master Boot Record) and a partition table recorded in the storage device corresponds to “system information”.
“Additional information of system information” refers to various types of information that can be used to select a target file or determine whether or not to refresh when refreshing file data or system information data. It means the information that you have. This information includes, for example, the recording time when the file was recorded immediately before, information indicating the importance of the file, a flag intended not to be refreshed, the number of times the refresh was performed, and the like. These pieces of information may be provided exclusively, or may use various information of files managed by the file system.

The fourth invention is the second invention, wherein the refresh control unit rewrites the data in the same area as the area read from the non-volatile storage device in the write instruction of the refresh process of the data constituting the file. Instruct the file manager.
The fifth invention is the third invention, wherein the refresh control unit rewrites the data in the same area as the area read from the non-volatile storage device in the instruction to refresh the data constituting the system information. Instruct the file manager to
A sixth invention is the second invention, wherein the refresh control unit rewrites the data in an area different from the area read from the nonvolatile storage device in the write instruction of the refresh process of the data constituting the file. Instruct the file manager.
The seventh invention is any one of the first, second, fourth, and sixth inventions, wherein the refresh control unit reads the file division data from the nonvolatile storage device to the file management unit, By instructing to repeat the operation of writing the read divided data into the nonvolatile storage device again, an instruction for refresh processing is issued to the entire file.

As a result, even if the file is composed of divided data, it is possible to reliably perform refresh processing in units of files.
Note that “divided data” includes, for example, a cluster.
The eighth invention is any one of the second, fourth, and sixth inventions, wherein the file selection unit selects a file to be refreshed during initialization processing of the nonvolatile storage device, and The refresh control unit is notified of the file identification information of the selected file.
Thereby, the refresh process can be performed when the nonvolatile memory device is initialized. Note that, at the time of initialization of the nonvolatile memory device, the memory access device is activated, the nonvolatile memory system configured by the memory access device and the nonvolatile memory device is activated, and the memory access device is nonvolatile. The case where the storage device is mounted and the nonvolatile storage system is in an operating state is included.

The ninth invention is any one of the second, fourth and sixth inventions, wherein the file selection unit sets the refresh processing target in a free time other than when the memory access device operates according to an instruction from the outside. The file identification information of the selected file is notified to the refresh control unit.
As a result, the refresh process can be performed during a so-called system idle time (for example, a time when the memory access device is not executing an externally instructed process), so that it can be efficiently performed without interfering with other processes. The refresh process can be performed in units of files.
A tenth invention is any one of the second, fourth, sixth, eighth, and ninth inventions, and further includes a clock unit that holds time information.

The additional information includes a write time that is a time when data is written to the nonvolatile storage device. The file management unit acquires time information indicating the time when the data constituting the file is written to the nonvolatile storage device from the clock unit, and uses the acquired time information as the write time of the additional information. The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the writing time of the additional information with a predetermined reference time, Based on this, the refresh process is notified.
In this memory access device, the refresh process is performed based on the elapsed time between the time when the file is written in the nonvolatile storage device and the current time, so that the refresh process can be performed in units of files with higher accuracy. .
The eleventh aspect of the present invention is the third or fifth aspect of the present invention, further comprising a clock unit that holds time information. The additional information includes a write time that is a time when data constituting the system information is written to the nonvolatile storage device. The file management unit acquires time information indicating the time at which the data to be refreshed is written in the nonvolatile storage device from the clock unit, and uses the acquired time information as the additional information write time. The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the writing time of the additional information with a predetermined reference time, Based on this, the refresh process is notified.

In this memory access device, since the refresh process is performed based on the elapsed time between the time when the data constituting the system information is written in the nonvolatile storage device and the current time, the necessity determination is performed, so that the accuracy is improved. The system information can be refreshed.
The twelfth invention is the tenth invention, wherein the additional information write time is information indicating the file creation date and time defined by the file system, and indicates the file creation or update date and time managed for each file. It is managed as information.
In this memory access device, the “file creation date”, which is information already defined and defined by the file system, can be shared, and the write time of the additional information can be written to the nonvolatile storage device. Therefore, in this memory access device, it is not necessary to provide a new entry separately from the conventional file system, and it is possible to perform refresh processing in units of files while realizing upward compatibility.

The thirteenth invention is any one of the second, fourth, sixth, eighth to tenth, and twelfth inventions, wherein the additional information includes file importance information, and the file selection unit is refreshed. The order of selecting files to be processed is determined based on importance information.
Thereby, it is possible to perform refresh processing for each file in consideration of the importance of the file. The “importance information” may be defined by the nonvolatile storage system or may be defined by the user.
A fourteenth invention includes a memory access device according to any one of the first to thirteenth inventions and a nonvolatile memory device. The nonvolatile memory device includes a nonvolatile memory and a memory controller that controls the nonvolatile memory.
A fifteenth aspect of the invention is a non-volatile storage device that writes / reads data in response to an external request, and includes a non-volatile memory, a memory controller, a refresh control unit, and a file management unit.

The memory controller controls the nonvolatile memory. The refresh control unit, for the file recorded in the nonvolatile memory managed by the file system, instructs to read data constituting only the file, and to write to the nonvolatile memory without changing the read data. The refresh process is instructed. In writing data for the refresh process, the file management unit writes data constituting the file to the nonvolatile memory, and writes related information managed by the file system regarding the data.
As a result, it is possible to instruct reading / writing of data on the nonvolatile storage device in units of files, so that refresh processing can be executed in units of files defined in a predetermined file system.

In this nonvolatile storage device, since the refresh control unit can instruct reading / writing of data on the nonvolatile memory in file units, the refresh process is executed in file units defined in a predetermined file system. Can do.
As a result, the data holding period can be made longer (extended) than the data holding period of the single nonvolatile memory.
The “file-based refresh process” is a concept that includes a refresh process that is executed on a part of data constituting a file. For example, a refresh process performed on a part of the data constituting the file may be performed on a file having a large file size, and the refresh process in this case is also included in the concept of “file unit refresh process”. It is.

In addition, “related information managed by the file system regarding data constituting a file” means information on the location of the storage area (for example, FAT) in the logical storage area managed by the file system and the data. This means information used in addition to the file data when the file system manages the file, such as various information of bibliographic items such as file write time, update time, access time, and file size (for example, Directory Entry).
The sixteenth invention is the fifteenth invention, wherein a file to be refreshed is selected based on additional information of a file recorded in a nonvolatile memory, and file identification information of the selected file is obtained. A file selection unit for notifying the refresh control unit is further provided. The refresh control unit instructs a refresh process for the file specified by the file identification information notified from the file selection unit. The file management unit further writes additional information to the nonvolatile memory.

As a result, a file to be refreshed can be selected based on the file additional information.
A seventeenth aspect of the invention is the sixteenth aspect of the invention, further comprising a clock unit that holds time information. The additional information includes a write time that is a time when data is written to the nonvolatile memory. The file management unit acquires time information indicating the time when the data constituting the file is written to the nonvolatile memory from the clock unit, and uses the acquired time information as a write time of the additional information. The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the writing time of the additional information with a predetermined reference time, Based on this, the refresh process is notified.
In this nonvolatile storage device, the refresh process is performed based on the elapsed time between the time when the file was written to the nonvolatile storage device and the current time, so the refresh process can be performed in units of files with higher accuracy. it can.

The eighteenth invention is the sixteenth invention, further comprising a time acquisition unit for acquiring time information from the outside. The additional information includes a write time that is a time when data is written to the nonvolatile memory. The file management unit obtains time information indicating the time when the data constituting the file is written to the nonvolatile memory from the outside via the time acquisition unit, and uses the obtained time information as a write time of the additional information. The file selection unit obtains time information indicating the current time from the outside via the time acquisition unit, and compares the elapsed time calculated from the time information indicating the current time and the write time of the additional information with a predetermined reference time. The refresh process is notified based on the comparison result.
As a result, even if the clock acquisition unit does not have a clock inside, by acquiring time information from the outside, the elapsed time between the time when the file was written to the nonvolatile storage device and the current time is obtained. Based on this, a refresh process can be performed.

A nineteenth aspect of the invention is a memory access method for writing / reading data to / from a non-volatile storage device having a non-volatile memory, comprising a refresh control step and a file management step.
In the refresh control step, for a file recorded in a nonvolatile storage device managed by the file system, a read instruction for data constituting only the file, and a write instruction to the nonvolatile storage device without changing the read data The refresh process is instructed. In the file management step, in writing the data for the refresh process, data constituting the file is written into the nonvolatile storage device, and related information managed by the file system is written with respect to the data.
As a result, a memory access method having the same effect as that of the first invention can be realized.

A twentieth aspect of the invention is a program for causing a computer to execute a memory access method for writing / reading data to / from a nonvolatile storage device including a nonvolatile memory. The memory access method includes a refresh control step and a file management step.
In the refresh control step, for a file recorded in a nonvolatile storage device managed by the file system, a read instruction for data constituting only the file, and a write instruction to the nonvolatile storage device without changing the read data The refresh process is instructed. In the file management step, in writing the data for the refresh process, data constituting the file is written into the nonvolatile storage device, and related information managed by the file system is written with respect to the data.
As a result, it is possible to realize a program that causes a computer to execute a memory access method that exhibits the same effects as those of the first invention.

A twenty-first invention is an integrated circuit used in a memory access device for writing / reading data to / from a non-volatile storage device having a non-volatile memory, and includes a refresh control unit and a file management unit.
The refresh control unit, for a file recorded in the nonvolatile storage device managed by the file system, instructs to read data constituting only the file, and to write to the nonvolatile storage device without changing the read data. The refresh process is instructed. In writing data for the refresh process, the file management unit writes data constituting the file to the nonvolatile storage device, and also writes related information managed by the file system regarding the data.
As a result, an integrated circuit used in the memory access device having the same effect as that of the first invention can be realized.

  According to the present invention, since the memory access device performs refresh in units of files, the data retention period can be made longer than the data retention period of the single nonvolatile memory even if the memory controller of the nonvolatile storage device does not support refresh. Can be long

Embodiments of the present invention will be described with reference to the drawings.
<1.1: Configuration of Nonvolatile Storage System>
FIG. 1 is a schematic configuration diagram of a nonvolatile storage system 101 according to the first embodiment of the present invention.
As illustrated in FIG. 1, the nonvolatile storage system 101 includes a memory access device 102 and a nonvolatile storage device 103.
(1.1.1: Configuration of memory access device)
The memory access device 102 has a function of writing data to the nonvolatile storage device 103 and reading data from the nonvolatile storage device 103 by designating an address.

The memory access device 102 includes a file control unit 110 that performs file management using a file system, and a clock unit 107. The file control unit 110 includes a file management unit 104, a file selection unit 105, and a refresh control unit 106.
The file management unit 104 reads / writes data, information, and the like with respect to the nonvolatile storage device 103. Examples of data and information that the file management unit 104 reads / writes from / to the nonvolatile storage device 103 include file data, correspondence between files and memory areas, system information, file identification information, and additional information.
When the file management unit 104 performs a writing process on the nonvolatile storage device 103, the additional information includes importance level information and the current time acquired from the clock unit 107. The importance level information may be information set by the user by inputting to the memory access device 102 via an external interface (not shown), or the memory access device based on the contents of the file in the memory access device 102 The information determined by 102 may be used.

The file selection unit 105 receives the file identification information and the additional information from the file management unit 104, preferentially selects a highly important file from the importance information in the additional information, and determines whether the file needs to be refreshed At this time, the current time is acquired from the clock unit 107, the elapsed time from the write time in the additional information is calculated, and if the elapsed time exceeds the reference time, it is determined that “refresh is necessary”, and the refresh control unit 106 File identification information.
In addition, the file selection unit 105 receives additional information from the file management unit 104 when determining whether system information needs to be refreshed, acquires the current time from the clock unit 107, and the elapsed time from the writing time in the additional information. When the elapsed time exceeds the reference time, it is determined that “refresh is necessary”, and a system information refresh notification is passed to the refresh control unit 106.

When the refresh control unit 106 receives file identification information or system information refresh notification from the file selection unit 105, the refresh control unit 106 performs “refresh” of the corresponding file or system information.
Specifically, the “refresh” is performed when the refresh control unit 106 issues a read instruction and a rewrite instruction to the file management unit 104, whereby the data in the nonvolatile storage device 103 is rewritten. At the time of rewriting, the file management unit 104 acquires the current time (time information) from the clock unit 107, updates the writing time in the additional information, and then rewrites to the nonvolatile storage device 103.
Here, the file control unit 110 of the memory access device 102 may be realized by software. For example, the memory access device 102 has a configuration in which a CPU, ROM, RAM, and the like are connected by bus, and a program that realizes the function of the file control unit 110 is stored in the ROM, and is executed by the CPU using the RAM. By doing so, the function of the file control unit 110 may be realized. In this case, it is compatible with a conventional file system (a file system not having a refresh function for each file) simply by installing a program to which the function of this embodiment (a refresh function for each file) is added to the memory access device 102. The function of the present embodiment (refresh function in units of files) is performed without reformatting the nonvolatile storage device 103 (reformatting the address space managed by the nonvolatile storage device 103) while maintaining the characteristics. Can be realized.

(1.1.2: Configuration of nonvolatile storage device)
The nonvolatile storage device 103 includes a memory controller 108 and a nonvolatile memory 109.
The nonvolatile memory 109 is a memory that keeps data even when the power is turned off, and is mainly realized by a flash memory. When a flash memory with an insufficient data retention period is used as the nonvolatile memory 109, the data retention period can be extended by “refresh” performed in the nonvolatile storage system 101 according to the present embodiment. Is particularly effective.
When receiving a write instruction from the memory access device 102, the memory controller 108 receives an address and data, and writes the data to a corresponding address on the nonvolatile memory 109. When there is a read instruction from the memory access device 102, the memory controller 108 receives an address from the memory access device 102, reads data existing at a corresponding address on the nonvolatile memory 109, and reads the read data to the memory access device. To 102. When the nonvolatile memory 109 is a flash memory, the memory controller 108 normally executes defect management (defect control), wear leveling (leveling of the number of rewrites), error correction processing by ECC, and the like. Therefore, the memory controller 108 executes an address conversion process. Specifically, the memory controller 108 designates an address (logical address) designated by the memory access device 102 to the nonvolatile storage device 103 and an address (physical address) designated by the memory controller 108 to the nonvolatile memory 109. Address). Since the memory controller 108 has such an address conversion function, the non-volatile storage device 103 is continuously connected to the memory access device 102 regardless of the data storage method in the non-volatile memory 109. An address space (a logical address space having contiguous addresses) can be provided.

≪Data allocation in non-volatile storage device (logical address space) ≫
Next, a data layout (logical address space) in the nonvolatile memory device will be described.
FIG. 2 is a diagram schematically showing a data layout diagram (logical address space) in the nonvolatile memory device 103 according to the first embodiment of the present invention.
The non-volatile storage device 103 can designate an area (address area) with a continuous address starting from “0”.
The system area 201 is located at address 0 of the nonvolatile storage device 103 and stores system information. The system information includes the total memory capacity of the nonvolatile storage device 103, the size of the system area 201, the size of the file management table 202, the size of the root directory area 203, and the size of the cluster 204. These pieces of information are written when the nonvolatile storage device 103 is formatted, but usually need not be rewritten unless reformatted. For this reason, in this embodiment, additional information is added to the system information, and the system area 201 is refreshed based on the additional information.

As shown in FIG. 2, the file management table 202 is arranged immediately after the system area 201, and the file management table 202 stores link information of the cluster 204 in which file data is stored. The file management table 202 reveals the correspondence between files and areas (address areas). Further, by referring to the file management table 202, it is possible to know which cluster 204 is free.
The root directory area 203 is arranged immediately after the file management table 202.
In general, a file system performs management by hierarchizing by a directory storing a plurality of files and directories. A directory located at the top of the hierarchical structure is called a “root directory”, and a directory located lower than it is called a “subdirectory”. The root directory area 203 stores a plurality of entries of files and directories existing in the root directory. When a new subdirectory is added to the root directory entry, an empty cluster 204 is allocated as a subdirectory area in order to store entries existing in the subdirectory. Furthermore, when a new subdirectory is added to the entry of the subdirectory, free clusters 204 are allocated in the same manner.

A plurality of clusters 204 are arranged from immediately after the root directory area 203 to the final area of the logical address space of the non-volatile storage device 103, and store file data or subdirectory entries as subdirectory areas. .
<< File management table >>
Next, the configuration of the file management table according to the present embodiment will be described.
FIG. 3 is a configuration diagram of a file management table according to the first embodiment of the present invention.
When the value in the file management table is 0x0000, the cluster number indicates “free cluster”. When the value in the file management table is from 0x0002 to MAX (the maximum value of the cluster number), this indicates that the cluster number is “in use”, and the value indicates the next cluster number, When the value in the file management table is 0xFFFF, the cluster number indicates the last cluster of the file.

The file management table in FIG. 3 shows an example in which the file “ABC” and the file “XYZ” exist.
The leading cluster of the file “ABC” is 0x0010, and it can be seen that the value stored therein is 0x0011 by referring to the contents of the cluster number 0x0010 in the file management table. That is, the second cluster of the file “ABC” is 0x0011.
Next, referring to the contents of the cluster number 0x0011 in the file management table, it can be seen that the value stored therein is 0x0013. That is, the third cluster of the file “ABC” is 0x0013.
Next, referring to the contents of the cluster number 0x0013 in the file management table, it can be seen that the value stored therein is 0xFFFF. This means that the cluster 0x0013 is the last cluster of the file “ABC”.

Thus, the file management table 202 shows that the file “ABC” is composed of clusters 0x0010, 0x0011, and 0x0013.
Similarly, it can be seen that the file “XYZ” is composed of clusters 0x0012 and 0x0015.
Further, referring to the contents of the cluster number 0x0014 in the file management table, it can be seen that the value stored therein is 0x0000. This means that cluster 0x0014 is an empty cluster. Normally, the file management table is updated when a new file is written in the nonvolatile storage device 103 or when a file update is performed such that the cluster occupied by the file is changed. When the file is refreshed, if the file is rewritten to another cluster, the file management table needs to be updated. Therefore, in this case, the file management table is refreshed at the same time when the file is refreshed.

On the other hand, when a file is refreshed, if the file is rewritten to the same cluster, it is not necessary to update the file management table, but the file management table may be rewritten with the same contents for the refresh.
<< Configuration of directory area >>
Next, the configuration of the directory area according to the present embodiment will be described.
FIG. 4 is a configuration diagram of the directory area according to the first embodiment of the present invention. The root directory area 203 and the subdirectory area have the configuration shown in FIG.
A plurality of entries are stored in the root directory area 203 and the subdirectory area. In FIG. 4, one line indicates one entry. Each entry includes an entry type, a file name or directory name, a leading cluster number of the file or directory, and additional information.

“Entry type” is “0”, indicating that the entry is “file”, and “1” is indicating that the entry is “subdirectory”.
“File name or directory name” is a character string. Although the same file name may exist in different directories, the path name that concatenates all subdirectory names and file names following the root directory with a specific delimiter between them is unique for each file, and file identification Can be information.
The “first cluster number” indicates the first cluster number of the file or directory. From the top cluster number of this file or directory, it can be seen where the data of the top cluster exists in the logical address space of the nonvolatile storage device 103. It can be known where the data of the second and subsequent clusters exist in the logical address space of the nonvolatile storage device 103 by following the corresponding first cluster number in the file management table 202. For example, in the case of the file “ABC” in the figure, the data of the first cluster exists in the cluster 0x0010, and the location of the data of the second and subsequent clusters is determined by tracing the file management table 202 from the position of the cluster number 0x0010. I can know.

“Additional information” includes “creation date and time” and “importance information”.
“Creation date” indicates time information (write time) when the file is written in the nonvolatile storage device 103. That is, when a file is written in the nonvolatile storage device 103, the current time (time information) at that time is written as “creation date”. This “creation date” is acquired by an external request. In this embodiment, since “creation date” is also used for refresh time management, “creation date” is updated at the time of refresh. That is, when the refresh is executed, the “creation date” is updated to the time information when the refresh is executed.
“Importance information” is a value indicating the importance of a file. That is, a value corresponding to the importance of the file is written as “importance information”. For example, in FIG. 4, if the importance is “normal”, “importance information” is set to “1”, if the importance is “somewhat important”, “importance information” is set to “2”, and if the importance is “important”. “Importance information” is set to “3”.

In addition, other information other than the above may be stored in the entries of the root directory area 203 and the subdirectory area. For example, when the file size is in bytes, it is necessary to store the number of bytes of the file. In this case, the “number of bytes of file” is included in the entries of the root directory area 203 and the subdirectory area.
<1.2: Operation of nonvolatile storage system>
Next, the operation (refresh process) of the nonvolatile storage system 101 will be described using a flowchart.
≪Refresh processing flowchart≫
FIG. 5 is a flowchart of the refresh process for all data according to the first embodiment of the present invention.

Steps S501 to S504:
First, the file selection unit 105 acquires system area additional information (S501), and performs a system area refresh determination process based on the acquired additional information (S502). From the result, the file selection unit 105 determines whether or not refreshing is necessary (S503).
If the file selection unit 105 determines that refresh is not necessary (when the determination result in step S503 is “NO”), the process proceeds to step S507.
On the other hand, when the file selection unit 105 determines that the refresh is necessary (when the determination result in step S503 is “YES”), the system area is refreshed (S504). Specifically, when the file selection unit 105 determines that refresh is necessary, the file selection unit 105 outputs a system information refresh notification to the refresh control unit 106, and the refresh control unit 106 When the system information refresh notification is received, the file management unit 104 is instructed to read and rewrite the system area. Then, the file management unit 104 reads and rewrites the system area with respect to the nonvolatile storage device 103 in accordance with the read instruction and the rewrite instruction from the refresh control unit 106. As a result, the system area is refreshed.

Steps S505 and S506:
Next, in step S505, it is determined whether or not the file management table 202 is to be refreshed. In step S505, it is determined to “execute” the refresh in the following case. That is, (1) when refreshing a file, when rewriting to the same cluster as the read cluster, and (2) not refreshing the file management table 202 when refreshing the file, that is, only the file management table 202 separately This is when it is necessary to refresh.
In other cases, it is not always necessary to refresh the file management table 202 in step S505.
If it is determined in step S505 that the refresh is “executed” (when the determination result in step S505 is “YES”), a step (S506) of refreshing the file management table 202 is performed.

On the other hand, when it is not determined in step S505 that the refresh is “executed” (when the determination result in step S505 is “NO”), the process proceeds to step S507.
Steps S507 to S513:
In step S507 and subsequent steps, refresh processing of each file (including subdirectories) is executed.
In step S507, the file selection unit 105 determines whether another file exists. If it is determined in step S507 that another file exists (if the determination result in step S507 is “YES”), the file selection unit 105 performs a step of selecting a file (S508). In step S508, a file or subdirectory is selected. Specifically, the file selection unit 105 selects a file by preferentially selecting a high importance item based on importance information in the additional information.

Next, a step (S509) of acquiring additional information of the file is executed, and a file refresh determination process is executed based on the acquired additional information (S510). It is determined from the determination result in step S510 whether or not refresh is necessary (S511), and when it is determined that refresh is necessary (when the determination result in step S511 is “YES”), a step of refreshing the file Is executed (S512).
On the other hand, when it is determined that the refresh is unnecessary (when the determination result in step S511 is “NO”), the process proceeds to step S507.
After step S512, the process returns to the step of determining whether another file exists (S507), and the same procedure is repeated. Then, the processes in steps S508 to S512 are performed for all files. In other words, when it is determined in step S507 whether or not there are other files (if the determination result in step S507 is “NO”), all data is refreshed. Ends (S513).

<< Refresh Determination Process (Steps S502 and S510) >>
Next, details of the refresh determination processing S502 and S510 will be described with reference to FIG.
FIG. 6 is a flowchart of the refresh determination process (S502, S510) according to the first embodiment of the present invention.
In step S <b> 601, the file selection unit 105 acquires the current time (time information) from the clock unit 107. Then, the file selection unit 105 calculates the elapsed time from the current time and the creation date and time in the additional information (S602).
Next, a step of determining whether or not the elapsed time exceeds the reference time (S603) is executed. Specifically, the file selection unit 105 takes the difference between the “current time” that is the time information acquired from the clock unit 107 and the “creation date” of the “additional information” acquired from the file management unit 104, “Elapsed time” (= “current time” − “creation date”) is obtained. Then, the file selection unit 105 compares the “elapsed time” with the “reference time”. If the “elapsed time” exceeds the “reference time”, the file selection unit 105 determines that “refresh is necessary” (S604). If not, it is determined that “refresh is not required” (S605).

Then, the refresh determination process ends (S606).
The “reference time” is preferably set in consideration of the characteristics of the nonvolatile memory 109 of the nonvolatile storage device 103.
<< File Refresh Process (Step S512) >>
Next, details of the file refresh processing S512 will be described with reference to FIG.
FIG. 7 is a flowchart of the file refresh process (S512) according to the first embodiment of the present invention.
Steps S701 to S706:
In step S701, a step of determining whether or not the end of the file is executed (S701). If it is determined from the determination result in step S701 that the end of the file is not yet reached (if the determination result in step S701 is “NO”), the next cluster data is refreshed (S702 to S706). ).

Next, processing in steps S702 to S706 will be described.
First, a step of determining a cluster from the leading cluster number and the file management table is executed (S702).
Next, a step of reading cluster data is executed (S703).
Then, a step of determining whether or not the refresh destination is a different cluster is executed (S704). The process of step S704 will be specifically described.
There are the following two methods for file refresh processing.
The first method is a method that does not change the FAT chain of the file that is the target of the file refresh process. For example, the file “ABC” in FIG. 3 includes clusters 0x0010, 0x0011, and 0x0013. The FAT chains of the file “ABC” are clusters 0x0010, 0x0011, and 0x0013. In the first method, the file is refreshed so as not to change the FAT chain.

The second method is a method of changing the FAT chain of a file to be subjected to a file refresh process. For example, when the file refresh process is executed for the file “ABC” in FIG. 3, in the second method, the FAT chain (for example, cluster 0x0016, 0x0017) different from the original FAT chain (cluster 0x0010, 0x0011, 0x0013) is used. , 0x0018), the file refresh process is performed.
In step S704, when the file is refreshed by the first method, it is determined that the refresh destination is “same cluster”. On the other hand, when the file is refreshed by the second method, it is determined that the refresh destination is “different cluster”.

If the refresh destination is a different cluster (if the determination result in step S704 is “YES”), a different cluster is selected in the step of determining the write destination cluster (S705), and the cluster data is written to the selected cluster (S706). .
On the other hand, when the refresh destination is the same cluster (when the determination result of step S704 is “NO”), the cluster data is written as the same cluster as the cluster from which the write destination has been read (S706).
In the second method, since the FAT chain is changed, when the file refresh process is executed by the second method, the contents of the file management table are automatically updated (file The management table will also be refreshed).
On the other hand, in the first method, since the FAT chain is not changed, it is necessary to separately determine whether or not to perform a refresh process on the file management table.

Note that it is effective to determine whether the file refresh process is executed by the first method or the second method in consideration of characteristics, specifications, and the like of the nonvolatile storage device 103. For example, when the first method is adopted in the nonvolatile storage device 103 used in the nonvolatile storage system 101, the physical address on the nonvolatile memory 109 to which the file is written is changed by the memory controller 108 before and after the refresh. However, when the second method is adopted, if the physical address on the non-volatile memory 109 to which the file is written is changed by the memory controller 108 before and after the refresh, the second method has a higher number of rewrites. Since leveling is performed and reliability is increased, it is preferable that the determination result in step 704 is “YES”.
After the process of step S706, the process returns to the step of determining whether the end of the file is reached (S701), and the same procedure is repeated.

Steps S707 to S712:
When the end of the file is reached, a step of determining whether the refresh destination is a different cluster is performed (S707). This is the same determination process as in S704, and the determination result in Step S707 is the same as the determination result in Step S704.
When the refresh destination is a different cluster (when the determination result in step S707 is “YES”), a step of updating the file management table is executed (S708). Simultaneously with the update of the file management table, the portion related to the file in the file management table is also refreshed. Note that this step may be performed immediately after the step of writing cluster data (S706) every time the cluster is refreshed, not after the refresh of the entire file is completed. In this case, however, the frequency of updating the file management table is increased.

On the other hand, in the step of determining whether the refresh destination is a different cluster (S707), if the refresh destination is the same cluster (if the determination result in step S707 is “NO”), whether or not to refresh the file management table is determined. A determination step is executed (S709). When the file management table is refreshed, a step of refreshing the file management table is executed (S710). If the determination result in step S707 is “NO” and the determination result in step S709 is “NO”, the file management table needs to be refreshed separately. In this case, the determination result in step S505 is “YES”. By doing so, the file management table can be separately refreshed at the same timing as the refresh of the system area.
Thereafter, a step of updating the entry (entry stored in the directory area) is executed (S711). At this time, the creation date and time in the additional information is updated to the current time acquired from the clock unit 107 by the file management unit 104. If the refresh destination is a different cluster in steps S704 and S707, the leading cluster number is also updated.

Then, the file refresh process ends (S712).
In the above description, the case where the file is refreshed in units of clusters has been described. However, the present invention is not limited to this, and the refresh may be performed with an arbitrary size. However, since refreshing with a large size requires a large buffer, it is desirable to perform with a suitable size. Further, for the convenience of file management, it is effective and efficient to simplify the procedure to perform refreshing in units of multiples of clusters.
In the nonvolatile storage system 101 of the present embodiment, the file creation date recorded at the time of file writing and acquired by an external request is used for refresh time management. However, the refresh time management is performed separately from the file creation date. May be provided in the additional information.

The file management system shown in the present embodiment is an example of a file system implementation. Actually, there are various file system systems such as FAT (File Allocation Table) and UDF (Universal Disk Format). The present invention is also applicable to such different schemes.
As described above, according to the nonvolatile storage system 101 of the present embodiment, the memory access device 102 refreshes data on the nonvolatile storage device 103 in units of files.
As a result, even if the memory controller included in the nonvolatile memory device does not support refresh (even if it does not have a refresh function), the data retention period is longer (extended) than the data retention period of the nonvolatile memory alone. can do.
Further, in the nonvolatile storage system 101 of the present embodiment, the nonvolatile storage device 103 does not need to have a clock unit for refresh time management, and the nonvolatile storage device 103 has time information (time information). Need not be obtained from the memory access device 102.

Further, in the nonvolatile storage system 101 of the present embodiment, when performing refresh by time management, the file creation date is used as a write time used for refresh (by sharing), and a new write time is set for refresh. There is no need to add (there is no need to add “refresh write time” to each entry in the directory area).
Further, in the nonvolatile storage system 101 of the present embodiment, when the file control unit 110 of the memory access device 102 is realized by software, that is, the memory access device 102 has a configuration in which a CPU, ROM, RAM, and the like are connected by bus. When realizing the function of the file control unit 110 by storing a program for realizing the function of the file control unit 110 in the ROM and executing the program while using the RAM by the CPU, the function ( Non-volatile storage while maintaining compatibility with conventional file systems (file systems that do not have a refresh function in units of files) simply by installing a program to which the refresh function in units of files) is added to the memory access device 102 Reformat device 103 Without reformatting) address space nonvolatile storage device 103 is managed, it may be to implement the functions of the present embodiment (refresh function in file units).

Furthermore, in the nonvolatile storage system 101 of the present embodiment, refreshing based on the importance level of a file can be performed by giving importance level information to the file.
[Other Embodiments]
≪First modification≫
In the above embodiment, the case where the memory access device 102 includes the file control unit 110 has been described. However, the file control unit 110 may be provided in the nonvolatile storage device. An example of this case will be described as a first modification.
FIG. 8 shows a schematic configuration diagram of a nonvolatile memory system 101A according to the first modification.
The same parts as those of the nonvolatile memory system 101 according to the first embodiment are denoted by the same reference numerals.

In the nonvolatile storage system 101A according to the first modified example, communication is performed with the file control unit 110 and the memory controller 108 of the nonvolatile storage device 103B via the IF unit 111 of the memory access device 102A.
In the nonvolatile storage system 101A, the time information of the clock unit 107 is input to the file management unit 104 and the file selection unit 105 of the file control unit 110 via the IF unit 111. Also, the importance level information is input to the file management unit 104 of the file control unit 110 via the IF unit 111. Thereby, in the non-volatile storage system 101A, since the input / output relationship is the same as that of the first embodiment, the same effect as that of the first embodiment can be obtained.
In FIG. 8, the file control unit 110 is a functional block different from the memory controller 108, but the file control unit 110 may be installed in the memory controller 108. Further, the file control unit 110 may be realized by software (program) in the memory controller 108.

≪Second modification≫
Further, in the nonvolatile memory system 101A according to the first modification, the clock unit 107 installed in the memory access device 102A may be provided in the nonvolatile memory device. An example of this case will be described as a second modification.
FIG. 9 shows a schematic configuration diagram of a nonvolatile memory system 101B according to the second modification.
In the nonvolatile memory system 101B according to the second modification, the clock unit 107 is installed in the nonvolatile memory device 103B, and in the memory access device 102B, the clock unit 107 is deleted from the memory access device 101A. Except for this point, it is the same as the nonvolatile memory system 101A according to the first modification. The non-volatile storage system 101B according to the second modification can achieve the same effects as those of the first embodiment.

In the nonvolatile storage system described in the above embodiment, each block may be individually made into one chip by a semiconductor device such as an LSI, or may be made into one chip so as to include a part or all of the blocks. .
Note that the name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied as a possibility.

Moreover, each process of the said embodiment may be implement | achieved by hardware, and may be implement | achieved by software. Further, it may be realized by mixed processing of software and hardware.
The specific configuration of the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the invention.

  The memory access device, nonvolatile storage device, nonvolatile storage system, memory access method, program, and integrated circuit of the present invention can extend (extend) the data retention period longer than the data retention period of the nonvolatile memory alone, Moreover, the introduction is easy. INDUSTRIAL APPLICABILITY The present invention is useful for AV equipment such as a digital camera, a digital video deck, or a personal computer that includes a nonvolatile storage device or that can be attached and detached.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which showed the non-volatile storage system in 1st Embodiment of this invention. The arrangement | positioning figure of the data in the non-volatile storage device in 1st Embodiment of this invention. The block diagram of the file management table in 1st Embodiment of this invention. The block diagram of the directory area | region in 1st Embodiment of this invention. 5 is a flowchart of refresh processing for all data according to the first embodiment of the present invention. The flowchart of the refresh determination process in 1st Embodiment of this invention. The flowchart of the refresh process of the file in 1st Embodiment of this invention. The schematic block diagram which showed the non-volatile memory system which concerns on the 1st modification of this invention. The schematic block diagram which showed the non-volatile memory system which concerns on the 2nd modification of this invention.

DESCRIPTION OF SYMBOLS 101 Nonvolatile memory system 102 Memory access device 103 Nonvolatile memory device 104 File management part 105 File selection part 106 Refresh control part 107 Clock part 108 Memory controller 109 Nonvolatile memory (flash memory)
110 File control unit

Claims (21)

A memory access device for writing / reading data to / from a nonvolatile storage device having a nonvolatile memory,
For a file recorded in the nonvolatile storage device managed by a file system, an instruction to read data constituting only the file and an instruction to write to the nonvolatile storage device without changing the read data A refresh control unit for instructing refresh processing at
In the data writing of the refresh process, a file management unit that writes data constituting the file to the nonvolatile storage device and writes related information managed by the file system with respect to the data;
A memory access device comprising: A file selection unit that selects a file to be refreshed based on additional information of the file recorded in the nonvolatile storage device, and notifies the refresh control unit of file identification information of the selected file; Prepared,
The refresh control unit instructs a refresh process for the file specified by the file identification information notified from the file selection unit;
The file management unit further writes the additional information to the nonvolatile storage device.
The memory access device according to claim 1. A memory access device for writing / reading data to / from a nonvolatile storage device having a nonvolatile memory,
A refresh control unit for instructing refresh processing by instructing reading of the data constituting the system information recorded in the nonvolatile storage device, and then instructing the nonvolatile storage device to write the read data;
A file selection unit for notifying the refresh control unit of a refresh process of the system information based on the additional information of the system information recorded in the nonvolatile storage device;
In the data writing of the refresh process, a file management unit for writing data constituting the system information to the nonvolatile storage device and writing additional information of the system information;
A memory access device comprising: The refresh control unit
Instructing the file management unit to rewrite the data in the same area as the area read from the nonvolatile storage device in the write instruction of the refresh process of the data constituting the file,
The memory access device according to claim 2. The refresh control unit
Instructing the file management unit to rewrite the data in the same area as the area read from the nonvolatile storage device in the write instruction of the refresh process of the data constituting the system information.
The memory access device according to claim 3. The refresh control unit
Instructing the file management unit to rewrite the data in an area different from the area read from the nonvolatile storage device in the write instruction of the refresh process of the data constituting the file.
The memory access device according to claim 2. The refresh control unit instructs the file management unit to repeat the operation of reading the divided data of the file from the nonvolatile storage device and writing the read divided data to the nonvolatile storage device again. And instructing the refresh process for the entire file.
The memory access device according to claim 1. The file selection unit selects a file to be refreshed during initialization processing of the nonvolatile storage device, and notifies the refresh control unit of file identification information of the selected file;
The memory access device according to claim 2. The file selection unit selects a file to be refreshed in a free time other than when the memory access device operates according to an instruction from the outside, and sends file identification information of the selected file to the refresh control unit. Notice,
The memory access device according to claim 2. It further includes a clock unit that holds time information,
The additional information includes a write time which is a time when data is written to the nonvolatile storage device,
The file management unit acquires time information indicating a time at which data constituting the file is written to the nonvolatile storage device from the clock unit, and the acquired time information is used as the writing time of the additional information,
The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the write time of the additional information with a predetermined reference time, Based on the comparison result, a refresh process is notified.
10. The memory access device according to claim 2, 4, 6, 8, or 9. It further includes a clock unit that holds time information,
The additional information includes a write time which is a time when data constituting the system information is written to the nonvolatile storage device,
The file management unit acquires time information indicating a time at which data to be subjected to the refresh process is written to the nonvolatile storage device from the clock unit, and the acquired time information is the writing time of the additional information. age,
The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the write time of the additional information with a predetermined reference time, Based on the comparison result, a refresh process is notified.
The memory access device according to claim 3. The writing time of the additional information is information indicating a file creation date and time defined by the file system, and is managed as information indicating a file creation or update date and time managed for each file.
The memory access device according to claim 10. The additional information includes importance information of the file,
The file selection unit determines an order of selecting a file to be refreshed based on the importance information;
13. The memory access device according to claim 2, 4, 6, 8 to 10, 12. A memory access device according to any one of claims 1 to 13,
A nonvolatile memory device comprising: a nonvolatile memory; and a memory controller that controls the nonvolatile memory;
A non-volatile storage system comprising: A non-volatile storage device for writing / reading data in response to an external request,
Non-volatile memory;
A memory controller for controlling the nonvolatile memory;
For a file recorded in the nonvolatile memory managed by a file system, an instruction to read data constituting only the file and an instruction to write to the nonvolatile memory without changing the read data A refresh control unit for instructing refresh processing at
In the data writing of the refresh process, a file management unit that writes data configuring the file to the nonvolatile memory and writes related information managed by the file system regarding the data;
A non-volatile storage device comprising: A file selection unit that selects a file to be refreshed based on the additional information of the file recorded in the non-volatile memory and notifies the refresh control unit of file identification information of the selected file; ,
The refresh control unit instructs a refresh process for the file specified by the file identification information notified from the file selection unit;
The file management unit further writes the additional information to the nonvolatile memory.
The nonvolatile memory device according to claim 15. It further includes a clock unit that holds time information,
The additional information includes a write time that is a time when data is written to the nonvolatile memory,
The file management unit acquires time information indicating the time when the data constituting the file is written to the nonvolatile memory from the clock unit, and the acquired time information is the writing time of the additional information,
The file selection unit acquires time information indicating the current time from the clock unit, compares the elapsed time calculated from the time information indicating the current time and the write time of the additional information with a predetermined reference time, Based on the comparison result, a refresh process is notified.
The nonvolatile memory device according to claim 16. It further includes a time acquisition unit that acquires time information from the outside,
The additional information includes a write time that is a time when data is written to the nonvolatile memory,
The file management unit acquires time information indicating a time at which data constituting the file is written to the nonvolatile memory from the outside via the time acquisition unit, and acquires the acquired time information of the additional information. Write time,
The file selection unit acquires time information indicating the current time from the outside via the time acquisition unit, and calculates an elapsed time calculated from the time information indicating the current time and the write time of the additional information according to a predetermined reference. Compare with the time and notify the refresh process based on the comparison result.
The nonvolatile memory device according to claim 16. A memory access method for writing / reading data to / from a non-volatile storage device including a non-volatile memory,
For a file recorded in the nonvolatile storage device managed by a file system, a read instruction for data constituting only the file and a write instruction to the nonvolatile storage apparatus without changing the read data A refresh control step for instructing refresh processing at
In the data writing of the refresh process, a file management step of writing data constituting the file to the nonvolatile storage device and writing related information managed by the file system regarding the data;
A memory access method comprising: A program for causing a computer to execute a memory access method for writing / reading data to / from a nonvolatile storage device including a nonvolatile memory,
For a file recorded in the nonvolatile storage device managed by a file system, a read instruction for data constituting only the file and a write instruction to the nonvolatile storage apparatus without changing the read data A refresh control step for instructing refresh processing at
In the data writing of the refresh process, a file management step of writing data constituting the file to the nonvolatile storage device and writing related information managed by the file system regarding the data;
A program for causing a computer to execute a memory access method. An integrated circuit used in a memory access device for writing / reading data to / from a nonvolatile storage device having a nonvolatile memory,
For a file recorded in the nonvolatile storage device managed by a file system, a read instruction for data constituting only the file and a write instruction to the nonvolatile storage apparatus without changing the read data A refresh control unit for instructing refresh processing at
In the data writing of the refresh process, a file management unit that writes data constituting the file to the nonvolatile storage device and writes related information managed by the file system with respect to the data;
An integrated circuit comprising:

Images