JP7548742B2 - Information processing device and information processing system for managing destinations for storing files in non-volatile memory - Google Patents

Description

The present invention relates to an information processing device and an information processing system that manage the destinations for files stored in non-volatile memory.

Control devices that control industrial machines such as machine tools are equipped with storage devices for storing control programs for controlling the industrial machines and for recording the operating status of the industrial machines. Control devices are often installed in environments where multiple industrial machines are operating, and operate under poor conditions where they are susceptible to the effects of vibrations and other factors. For this reason, control devices sometimes use semiconductor storage that uses NAND flash as a storage device, which has no moving parts and is less susceptible to the effects of vibrations.

In non-volatile memory that uses NAND flash, such as SSDs (Solid State Drives), data is written and read in units called pages, which are collections of memory cells. Data written to a page is erased in units called blocks, which are collections of multiple pages. Since flash memory does not allow data to be overwritten, when changing data within a page, the data in the entire block that contains that page is temporarily saved, the block is erased, and then the entire block is written back together with the changed data.

The memory cells of flash memory using NAND flash are degraded by electrons penetrating the oxide film, which acts as an insulator in terms of the operating principle, and so the number of times they can be written is limited. For this reason, in flash memory, the number of writes and erases for each block is counted, and write control (wear leveling) is performed so that the number of writes and erases for each block is as uniform as possible. Therefore, the lifespan of the flash memory can be managed by obtaining the number of writes and erases for the block with the most number of writes and erases from the flash memory. For example, an alarm can be output if the number of writes and erases for the block with the most number of writes and erases exceeds 90% of the maximum number of writes and erases allowed, allowing flash memory that is approaching the end of its life to be replaced.

On the other hand, there is a non-volatile memory that does not have a configuration that is electrically degraded, unlike a flash memory. In this disclosure, such a non-volatile memory is called a non-volatile memory with no write count limit. Examples of non-volatile memories with no write count limit include MRAM and battery-backed SRAM.
Non-volatile memory without a write count limit generally has a high cost per capacity. Therefore, in order to reduce the hardware cost of non-volatile memory, some conventional devices are equipped with both non-volatile memory with a write count limit and non-volatile memory without a write count limit, and store files with low write frequency in the non-volatile memory with a write count limit and files with high write frequency in the non-volatile memory without a write count limit.

However, the write frequency is not known in advance, and there are files whose write frequency changes depending on the usage of the control device, the usage of the machine to be controlled, and the usage of each machine's functions. It is not possible to know which data is written to frequently before using the control device.

As a technology for storing frequently written files in non-volatile memory with no limit on the number of writes, there is a technology that stores files from a certain task in non-volatile memory with no limit on the number of writes if the amount of writing (or the frequency of writing or the number of writes) to flash memory from that task is higher than a certain threshold. For example, see Patent Document 1.

Patent Publication No. 6193834

Non-volatile memory with no limit on the number of times it can be written has a high cost per unit of capacity, so it is common to estimate the approximate amount of usage before starting to use it and install non-volatile memory with the minimum capacity required. Therefore, if more writing is done than expected, it will be necessary to replace it with non-volatile memory with a larger capacity.

Replacing non-volatile memory is costly and time-consuming. To make effective use of hardware resources, it is better to be able to continue using the non-volatile memory originally installed without having to replace it.

When using both non-volatile memory with no write limit and non-volatile memory with a write limit, there is a need for technology that efficiently distributes files and extends the lifespan of the non-volatile memory with a write limit so that the originally installed non-volatile memory can continue to be used without replacing it.

One aspect of the present disclosure is an information processing device comprising: a first non-volatile memory with no limit on the number of writes; a second non-volatile memory with a limit on the number of writes; a normal task execution unit that executes normal tasks; a file information storage unit that stores a file write history in the normal tasks; a file save destination determination unit that determines a save destination of a file stored in the file information storage unit based on the file write history so that the write frequency of the second non-volatile memory is low; a file save destination change unit that saves the file in the first non-volatile memory or the second non-volatile memory in accordance with the save destination determined by the file save destination determination unit; a relocation execution unit that relocates a file to be stored in the first non-volatile memory or the second non-volatile memory based on the save destination of the file determined by the file save destination determination unit; and a relocation file information storage unit that stores identification information of a file for which relocation is being performed, and the relocation execution unit resumes the relocation based on the identification information if the relocation is interrupted .

One aspect of the present disclosure is an information processing system comprising: a first non-volatile memory with no limit on the number of writes; a second non-volatile memory with a limit on the number of writes; a normal task execution unit that executes normal tasks; a file information storage unit that stores a file write history in the normal task; a file storage destination determination unit that determines a storage destination of a file stored in the file information storage unit based on the file write history so that the write frequency of the second non-volatile memory is low; a file storage destination change unit that saves the file in the first non-volatile memory or the second non -volatile memory in accordance with the storage destination determined by the file storage destination determination unit; a relocation execution unit that relocates a file stored in the first non-volatile memory or the second non-volatile memory based on the storage destination of the file determined by the file storage destination determination unit; and a relocation file information storage unit that stores identification information of a file for which relocation is being performed, and the relocation execution unit resumes the relocation based on the identification information if the relocation is interrupted .

According to the present disclosure, when using both non-volatile memory with no write count limit and non-volatile memory with a write count limit, files can be distributed efficiently and the lifespan of the non-volatile memory with a write count limit can be extended.

FIG. 2 is a hardware configuration diagram of an information processing device according to the present disclosure. FIG. 1 is a block diagram of an information processing apparatus according to a first disclosure. FIG. 4 illustrates an example of a file information storage unit. FIG. 13 is a diagram showing an example of a write history to a non-volatile memory. 11 is a diagram showing an example of a combination of files, a total used capacity of a first nonvolatile memory, and a total write frequency of a second nonvolatile memory; FIG. FIG. 13 is a block diagram of an information processing apparatus according to a second disclosure. FIG. 13 is a diagram illustrating an example of a file storage unit when writing frequency correction is performed. 1 is a block diagram of an information processing device including a reallocation execution unit. 13 is a flowchart illustrating a reallocation process. 1 is a block diagram of an information processing device in which a file information storage unit is provided in a first nonvolatile memory. FIG. 11 is a block diagram of an information processing device in which a file information storage unit is provided in a second nonvolatile memory. FIG. 11 is a block diagram of an information processing device in which a file information storage unit is provided in a third nonvolatile memory.

[First Disclosure]
An example of the information processing device 1 of the present disclosure is shown below. The information processing device 1 can be implemented as a control device that controls industrial machinery such as a machine tool. The present disclosure is applied to the information processing device 1 that uses both a non-volatile memory with no write count limit and a non-volatile memory with a write count limit, and the type of the information processing device 1 is not particularly limited.

As shown in FIG. 1, the information processing device 1 includes a CPU 111 that controls the entire information processing device 1, a ROM 112 that records programs and data, and a RAM 113 for temporarily expanding data. The CPU 111 reads the system program recorded in the ROM 112 via a bus 120, and controls the entire information processing device 1 in accordance with the system program.

The interface 115 is an interface for connecting the information processing device 1 to an external device 121 such as an adapter. Programs, various parameters, etc. are read from the external device 121. In addition, programs, various parameters, etc. edited within the information processing device 1 may be stored in an external storage means via the external device 121.

The information processing device 1 is connected to the display unit 122 via the interface 116. The information processing device 1 performs file management, which will be described later. Programs for file management are stored in a first non-volatile memory 124, a second non-volatile memory 125, and a third non-volatile memory 127, which will be described later.

The nonvolatile memories include a first nonvolatile memory 124 that has no limit on the number of writes, and a second nonvolatile memory 125 that has a limit on the number of writes. The first driver 118 receives file read and write requests from the CPU 111, and controls reading and writing of data to the first nonvolatile memory 124. The second driver 119 receives file read and write requests from the CPU 111, and controls reading and writing of data to the second nonvolatile memory 125.
The first non-volatile memory 124 is an MRAM or a battery-backed SRAM. MRAM is a type of semiconductor memory that uses a magnetic material as part of the material of the memory element, and records signals by changing magnetization. The recorded information is not erased even if the power is lost. SRAM is a type of volatile semiconductor memory, but it can be used as a non-volatile memory that does not lose its contents even when the power of the device body is turned off by combining it with a small battery. The first non-volatile memory 124 has no driving part and is resistant to shocks and vibrations, making it suitable for use in factories, etc., but the cost per capacity is high and the usable capacity is limited.
The second non-volatile memory 125 is, for example, a flash memory. A flash memory is a type of storage device that uses a semiconductor element, and can be written to repeatedly, and the stored contents are maintained even when the power is turned off. Since flash memory has no moving parts and is resistant to shocks and vibrations, it is suitable for use in factories, etc., but the number of times it can be written to is limited due to the structure of the element.

The first non-volatile memory 124 and the second non-volatile memory 125 store programs read from the external device 121 via the interfaces 115, 116, and 117, user operations input via the input unit, and various data (e.g., setting parameters, sensor information, etc.) acquired from each part of the information processing device 1 and industrial machinery, etc.

[First Disclosure]
2 is a block diagram of the information processing device 1 of the present disclosure. The information processing device 1 includes a normal task execution unit 11 that executes normal tasks that the information processing device should normally perform, a file information storage unit 12 that stores file writing history in normal tasks, and a file management unit 13 that manages the file storage destination (first non-volatile memory 124 or second non-volatile memory 125).

The normal task execution unit 11 executes all tasks except for the file management of this disclosure. Such tasks are called normal tasks. A normal task is not a special task, but refers to all tasks necessary for the operation of the information processing device 1. For example, if the information processing device 1 is a numerical control device, the information processing device 1 analyzes a machining program, generates commands for a machine tool, and outputs the generated commands. In addition, when an error occurs, it issues a warning or stops the machine. It accepts input from the user and accepts various setting changes. A normal task refers to all tasks executed when the information processing device 1 is operated.

The file information storage unit 12 normally stores the file writing history and the file save destination in the task execution unit 11. The file information storage unit 12 in FIG. 3 stores the file name, file write frequency, file size, and save destination information. The write frequency is the number of writes per day for each file. The write frequency is calculated by dividing the total number of writes for the file by the number of days. The file size is the file size of each file. The save destination information records whether the save destination for each file is the first non-volatile memory 124 or the second non-volatile memory 125. Until the file management unit 13 determines the save destination for the file, the save destination information records the default save destination. The default save destination is, for example, but is not limited to, the save destination predicted before starting to use the information processing device 1.

The file management unit 13 has a file storage destination change request unit 14 that instructs the start of file management, a file storage destination determination unit 15 that determines whether to store the file in the first non-volatile memory 124 or the second non-volatile memory 125, and a file storage destination change unit 16 that saves the file in the determined storage destination.

The file destination change request unit 14 starts the process of changing the file destination. The file destination change request unit 14 can set the start timing of the process of changing the file destination. The start timing can be, for example, when a power-on time set in advance has elapsed, when a time set by the user has elapsed, or when the writing frequency of the second non-volatile memory 125 has exceeded a certain threshold. The condition for the start timing may be set in advance or may be set as a default.
As an application, the file write frequency and the operating status of the information processing device 1 may be stored in association with each other, and when the operating status of the information processing device 1 changes, a request to change the save destination may be output and the save destination of the file may be determined based on the write frequency associated with the operating status.

When the file destination determination unit 15 receives a request to change the destination, it determines the destination for each file based on the write history recorded in the file information storage unit 12 so as to reduce the writing frequency to the second non-volatile memory 125.

The file storage destination change unit 16 outputs a command to the first driver 118 and the second driver 119 to store the file in the determined storage destination (the first non-volatile memory 124 or the second non-volatile memory 125).

[File save destination determination method]
An example of a method for determining a file storage destination is shown below. In this example, for all combinations of file storage destinations, the total usage capacity of the first non-volatile memory 124 and the total writing frequency of the second non-volatile memory 125 are calculated for each combination by referring to the file write history stored in the file information storage unit 12.
As a result, the combination in which the total usage capacity of the first non-volatile memory 124 does not exceed the upper capacity limit of the first non-volatile memory 124 and the total writing frequency of the second non-volatile memory 125 is the lowest is adopted.

For example, in Figure 4, looking at the write history, four files, file 1 to file 4, have been written, the file sizes of file 1 to file 4 are 300 Kbytes, 500 Kbytes, 800 Kbytes, and 200 Kbytes, respectively, and the write frequency per day of file 1 to file 4 is 4 times, 5 times, 10 times, and 3 times.

The combinations of the four files, the total usage amount of the first non-volatile memory 124, and the total write frequency of the second non-volatile memory 125 for each combination are as shown in FIG.
For each combination, the combinations in which the total file capacity allocated to the first non-volatile memory 124 (hereinafter referred to as the total used capacity of the first non-volatile memory 124) is less than the maximum capacity of the first non-volatile memory 124 (1024 Kbytes) are combinations 1 to 5 and combinations 9 to 13.
Among the combinations in which the total used capacity of the first non-volatile memory 124 does not exceed the maximum capacity of the first non-volatile memory 124, the combination in which the total write frequency of the second non-volatile memory 125 is the lowest is combination 13. Based on this result, the file storage destination determination unit 15 determines that the storage destination of files 1 and 2 is the second non-volatile memory 125, and the storage destination of files 3 and 4 is the first non-volatile memory 124.

The method of determining the file storage destination is not limited to the above-mentioned method. For example, the file information storage unit 12 may be referenced, and files with the most frequent write counts may be allocated to the first non-volatile memory 124, and when the total capacity of the allocated files exceeds the maximum capacity of the first non-volatile memory 124, the subsequent files may be allocated to the second non-volatile memory 125.
The file destination determination unit 15 determines a destination for each file based on the writing history of the file stored in the file information storage unit 12 so that the writing frequency to the second non-volatile memory 125 is low.

[Second Disclosure]
6 is a block diagram of the information processing device 1 according to the second disclosure. In the second disclosure, the information processing device 1 includes a writing frequency correction unit 17.
The write frequency correction unit 17 excludes data in the write history that shows a large temporary change in the write frequency. For example, the file write frequency temporarily increases during machine adjustment. The write frequency correction unit 17 performs, for example, quartiles or outlier testing, and excludes data for a period when the write frequency is high or low from the write history.

7 shows an example of the file information storage unit 12 when modifying the writing frequency. When modifying the writing frequency, the writing frequency for each file is recorded for each predetermined time. In FIG. 7(a), the writing frequency for each day and time is recorded, for example, the first day, the second day, and so on.
7B, if the write frequency of a certain file is 9 times on the first day, 11 times on the second day, 100 times on the third day, and 10 times on the fourth day, only the third day fluctuates greatly. The write frequency correction unit 17 excludes the data for the third day and calculates the average of the first, second, and fourth days. The average value is 10 times/day, and this value becomes the corrected write frequency.

The file save destination is calculated based on the revised write frequency. By correcting the write frequency, file management can be performed efficiently under normal usage conditions without being affected by temporary changes, such as 100 writes on the third day.

[File relocation]
When the destination to save the file has been determined, the file needs to be relocated in order to move the file to the determined destination. The information processing device 1 in Fig. 8 includes a relocation execution unit 18. The relocation execution unit 18 relocates the file as follows.
First, in accordance with the destination information in the file information storage unit 12, a file is moved from the first non-volatile memory 124 to the second non-volatile memory 125. The reason why the file is moved from the first non-volatile memory 124 to the second non-volatile memory 125 first is that the capacity of the second non-volatile memory 125 is large and there is free memory space.
Next, in accordance with the destination information in the file information storage unit 12, the files recorded in the second non-volatile memory 125 are moved to the first non-volatile memory 124. When all the files recorded in the file information storage unit 12 have been moved, the relocation of the files is completed.

The information processing device 1 may stop due to a power outage, an error, etc. The relocation execution unit 18 stores information about the file being relocated in order to resume the relocation process even if it is interrupted.
In the present disclosure, it is assumed that the files stored in the file information storage unit 12 are assigned file numbers such as file 1, file 2, file 3, .... Each time a file is moved, the relocation file information storage unit 19 stores the number N of the moved file. The last file number in the file information storage unit 12 is called the maximum file number.

The rearrangement process will be described with reference to FIG.
The relocation execution unit 18 first sets the file number N to 1 (step S1). This indicates that file 1 is the target of the relocation process. Next, the file information storage unit 12 is referenced, and if file N is a file to be moved from the first non-volatile memory 124 to the second non-volatile memory 125, file N is moved from the first non-volatile memory 124 to the second non-volatile memory 125 (step S2). When the relocation process of file N is completed, the file number is incremented by 1 (step S3).

The relocation execution unit 18 compares the file number N incremented in step S3 with the maximum file number in the file information storage unit 12, and if the file number N is less than or equal to the maximum file number (step S4; No), it proceeds to step S2 and performs the relocation process for file N.
If the file number N exceeds the maximum file number (step S4; Yes), the transfer of the file from the first non-volatile memory 124 to the second non-volatile memory 125 is completed. The relocation execution unit 18 proceeds to the process of step S5.

The relocation execution unit 18 sets the file number N to 1 (step S5). This indicates that file 1 is the target of the relocation process. Next, the file information storage unit 12 is referenced, and if file N is a file to be moved from the second non-volatile memory 125 to the first non-volatile memory 124, file N is moved from the second non-volatile memory 125 to the first non-volatile memory 124 (step S6). When the relocation process for file N is completed, the file number is incremented by 1 (step S7).

The relocation execution unit 18 compares the file number N incremented in step S3 with the maximum file number in the file information storage unit 12, and if the file number N is less than or equal to the maximum file number (step S8; No), it proceeds to step S6 and performs the relocation process for file N.
If the file number N exceeds the maximum file number (Step S8; Yes), the transfer of the file from the second non-volatile memory 125 to the first non-volatile memory 124 is completed.
Finally, the relocation execution unit 18 assigns 0 to the file number N in the relocation file information storage unit 19, and ends the relocation process (step S9).

The relocation execution unit 18 relocates files from the first non-volatile memory 124 to the second non-volatile memory 125 in steps S1 to S4, and relocates files from the second non-volatile memory 125 to the first non-volatile memory 124 in steps S5 to S8.
When the relocation process is interrupted, a file number N other than 0 is stored in the relocation file information storage unit 19 .
If the value of file number N in the relocation file information storage unit 19 is the file number of a file to be stored in the second non-volatile memory 125, it is determined that the processing was interrupted immediately after step S2 for file number N, and processing is resumed from step S2 for the file with file number N+1.
If the value of file number N in the relocation file information storage unit 19 is the file number of a file to be stored in the first non-volatile memory 124, it is determined that the processing was interrupted immediately after step S6 for file number N, and processing is resumed from step S6 for the file with file number N+1.

[File information storage destination]
The file information storage unit 12 stores the information in any one of the first non-volatile memory 124 , the second non-volatile memory 125 , and the third non-volatile memory 127 .
10 shows an example in which a file information storage unit 12 is provided in the first non-volatile memory 124. Providing the file information storage unit 12 in the first non-volatile memory 124 has the effect that writing to the file information storage unit does not affect the lifespan of the second non-volatile memory.

Figure 11 shows an example in which a file information storage unit 12 is provided in the second non-volatile memory 125. Providing a file information storage unit 12 in the second non-volatile memory 125 has the advantage that the capacity of the file information storage unit does not affect the capacity used by the first non-volatile memory, which has a high cost per capacity.

Figure 13 shows an example in which a file information storage unit 12 is provided in the third non-volatile memory 127. Providing a file information storage unit 12 in the third non-volatile memory 127 has the advantage that writing to the file information storage unit does not affect the lifespan of the second non-volatile memory, and furthermore, the capacity of the file information storage unit does not affect the capacity used by the first non-volatile memory, which has a high cost per capacity.

As described above, the information processing device 1 according to the present disclosure includes at least two non-volatile memories 124, 125, a first non-volatile memory 124 with no limit on the number of writes and a second non-volatile memory 125 with a limit on the number of writes, and while the normal task execution unit 11 is executing a normal task, creates a file write history in the file information storage unit 12, and determines the save destination of each file based on the file write history so that the writing frequency to the second non-volatile memory 125 is low.

In addition, based on the file writing history, the file storage destination is determined so that as many files as possible are stored in the first non-volatile memory 124, which has no limit on the number of times it can be written.

By excluding data whose write frequency fluctuates greatly, file management can be achieved that functions efficiently under steady-state usage conditions without being affected by temporary changes.

In addition to deciding where to save the file, it also relocates the file to the decided save destination. When relocating, it remembers the file number of the file that was moved. This means that even if the process is interrupted, it can be resumed continuously.

REFERENCE SIGNS LIST 1 Information processing device 11 Normal task execution unit 12 File information storage unit 13 File management unit 14 File storage destination change request unit 15 File storage destination determination unit 16 File storage destination change unit 17 Write frequency correction unit 18 Relocation execution unit 19 Relocation file information storage unit 111 CPU
118 First driver 119 Second driver 122 Display unit 123 Input unit 124 First non-volatile memory 125 Second non-volatile memory 126 Third driver 127 Third non-volatile memory

Claims (10)

a first non-volatile memory having no limit on the number of write operations;
a second non-volatile memory having a write limit;
a normal task execution unit that executes normal tasks;
a file information storage unit that stores a write history of a file in the normal task;
a file destination determination unit that determines a destination for storing the file stored in the file information storage unit based on the write history of the file so that the write frequency of the second non-volatile memory is low;
a file destination change unit that causes a file to be saved in the first non-volatile memory or the second non-volatile memory according to the destination determined by the file destination determination unit;
a relocation execution unit that relocates a file to be stored in the first non-volatile memory or the second non-volatile memory based on the file storage destination determined by the file storage destination determination unit;
a relocation file information storage unit that stores identification information of a file for which relocation is being executed;
Equipped with
the reallocation execution unit resumes the reallocation based on the identification information when the reallocation is interrupted;
Information processing device. The information processing device according to claim 1, wherein the file write history includes at least the write frequency and file size of each file. The information processing device according to claim 1, wherein the file save destination determination unit determines the save destination of each file based on the writing history of the file so as not to exceed the upper limit of the file capacity of the first non-volatile memory and so as to reduce the writing frequency of the second non-volatile memory. The information processing device according to claim 1, wherein the file storage destination determination unit determines a combination of file storage destinations based on the file writing history such that the upper limit of the file capacity of the first non-volatile memory is not exceeded and the writing frequency of the second non-volatile memory is low. The information processing device according to claim 1, further comprising a file save destination change request unit that requests the start of changing the save destination of the file according to a preset condition. The information processing device according to claim 1, further comprising a write frequency correction unit that excludes a write frequency that changes temporarily from the write frequency of the second non-volatile memory. The information processing device according to claim 1, wherein the file information storage unit is provided in the first non-volatile memory. The information processing device according to claim 1, wherein the file information storage unit is provided in the second non-volatile memory. The information processing device according to claim 1, wherein the file information storage unit is provided in a third non-volatile memory different from the first non-volatile memory and the second non-volatile memory. a first non-volatile memory having no limit on the number of write operations;
a second non-volatile memory having a write limit;
a normal task execution unit that executes normal tasks;
a file information storage unit that stores a write history of a file in the normal task;
a file destination determination unit that determines a destination for storing the file stored in the file information storage unit based on the write history of the file so that the write frequency of the second non-volatile memory is low;
a file destination change unit that causes a file to be saved in the first non-volatile memory or the second non-volatile memory according to the destination determined by the file destination determination unit;
a relocation execution unit that relocates a file to be stored in the first non-volatile memory or the second non-volatile memory based on the file storage destination determined by the file storage destination determination unit;
a relocation file information storage unit that stores identification information of a file for which relocation is being executed;
Equipped with
the reallocation execution unit resumes the reallocation based on the identification information when the reallocation is interrupted;
Information processing system.

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