JPH10326227A - System for managing storage device using flash memory as storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a management system in which a storage device using a flash memory as a storage medium can be replaced with a hard disk device, and the long life of the storage device can be obtained. SOLUTION: A storage device is provided as an FEEPROM disk 104, and constituted of three areas, that is, a disk area 301, substitute page area 302, and substrate page management area 303. Also, this device is provided with a managing means 102 equipped with a file system 203 for managing this disk device by the same method as a hard disk device, and a device driver 204 for controlling the writing/reading of the disk device by the same interface is the file system of the hard disk device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device using a flash memory as a storage medium, and using the flash memory for managing writing / reading of data to / from the storage device by a file system. Regarding the management method.

[0002]

2. Description of the Related Art At present, a magnetic disk device (hard disk device) is used as a storage medium for storing data in a data transmission device or the like. The life of a hard disk is said to be about two years (20,000 hours). In addition to the need for periodic replacement, there are many failures of the hard disk itself, and its maintenance is troublesome. Therefore, it is considered to use a flash EEPROM (hereinafter referred to as a flash memory) having less failures in place of the hard disk to reduce maintenance. Is the limit.

As is well known, in a nonvolatile semiconductor memory, writing (or erasing) is performed by injecting electrons into a floating gate of a memory element. However, as the number of times increases, an oxide film under the floating gate deteriorates. ,
The reliability of data written in this area cannot be obtained. Therefore, the function of the magnetic disk cannot be unconditionally substituted by the flash memory.

As a prior art for solving the problem of the limitation of the number of times of writing of the flash memory, there is Japanese Patent Application Laid-Open No. 6-282484 (referred to as a first prior art). In the first prior art, write control is performed by counting the number of times data has been written to a flash memory using a block write detection circuit. That is, as shown in FIG. 7, a data write management device for a flash memory, in which writing (and erasing) of each block of the flash memory 73 is performed.
Block write detection circuit 72 for detecting that the operation has been performed. The CPU 71 counts the number of times of writing for each block, and writes new data preferentially for a block with a small number of times of writing. Therefore, data writing is performed on each block of the flash memory on average, so that data writing is not concentrated on some blocks, and the life of the flash memory can be extended.

Japanese Patent Laid-Open Publication No. Hei 6-332806 (second
Discloses a technique of performing write control of a flash memory by using a circuit for performing write control in a semiconductor disk device. That is, as shown in FIG. 8, a semiconductor disk control circuit 801 for performing a write control is provided in a semiconductor disk device 80 to perform a write control of a flash memory.

[0006]

As described above, in the first prior art, the write control is performed by counting the number of times of writing in the flash memory. However, when a write error occurs, There is no remedy. That is, if an error occurs in some area because there is no substitute memory area, there is a disadvantage that the storage device has a limited life at that point. The second prior art is a write control method in a semiconductor disk device.
Existing systems cannot be fully utilized. In other words, no consideration is given to control in a device in which a hard disk is connected to the same bus, and reconfiguration of a special circuit or software level when changing an existing hard disk to a storage device using flash memory as a storage medium Is required. The present invention has been made to solve such a problem.

[0007]

According to the present invention, there is provided a storage system using a flash memory as a storage medium according to the present invention.
A storage device using a flash memory as a storage medium and a storage device storing a management device configured by a program are connected to the U bus, and the management device manages writing / reading of data to / from the storage device. In a management method of a storage device using a flash memory as a storage medium, the storage device is
A disk device using a flash memory as a storage medium,
A file system that manages data blocks of the disk device;
A device driver for controlling reading; an operating system for controlling the file system and the device driver; a means for the file system to manage the disk device in the same manner as a hard disk device; and the device driver for the hard disk device. Means for controlling writing / reading to / from the disk device using the same interface as the file system of the above (1), wherein the management means manages writing / reading of data to / from the storage device.

[0008] Further, the interface is a SCSI (s)
mall computer system interface).

The storage means may be a ROM (or R
AM and ROM).

[0010] Further, the disk device rewrites a disk area for storing a data block managed by the file system with a memory address attached thereto and a write failure in any of the data blocks in the disk area. A replacement page area for storing a replacement block for writing a data block with the same memory address as the data block, and a replacement page management area for storing an address block for writing a memory address of a data block in the rewritten disk area In response to a write / read request of a data block from the file system to the disk area of the disk device, the device driver searches for an address block of the alternative page management area. Write / read to / from disk area, or Characterized in that it managed or write / read to the serial alternative page area.

When writing a data block into the disk area results in an error in writing to the disk area, the device driver searches for an unused address block in the alternative page management area. If there is an unused address block, the address of the write request data block is written to the address block, and the write request data block is written to a replacement block of the replacement page area corresponding to the address block. It is characterized by performing.

When writing a data block to the replacement page area results in an error in writing to the replacement page area, the disk driver sets an unused address block in the replacement page management area. And if there is an unused address block, write an unwritable mark in the address block of the alternative page management area where the address of the write request data block was written before the search, and The address of the write request data block is written to the address block, and the write request data block is written to a substitute block of the substitute page area corresponding to the address block.

[0013] Further, when writing the data block to the alternative page area when an error occurs during the writing of the data block to the alternative page area, the disk driver sets an unused address in the alternative page management area. The system further comprises means for searching for a block and notifying the operating system of a write error when there is no unused address block.

The present invention is configured as described above,
It is possible to replace a storage device using a flash memory as a storage medium with a hard disk device without requiring a special circuit, and to change from a hard disk incorporated in the device to the storage device, a device driver is newly installed. Can be done by itself, and the reusability at the software level is increased. Further, the disk area, the alternative page area,
By providing three areas of the alternative page management area, the life of the storage device can be extended.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a hardware configuration for explaining the present invention. In the figure, 101 is a CPU, 102 is a RAM, 1
Reference numeral 03 denotes a ROM. In this specification, the RAM 102 and the ROM 103 are also referred to as storage means. Reference numeral 104 denotes a disk device using a flash memory as a storage medium (hereinafter, referred to as FEEPROM); 105, an address bus; and 106, a data bus. Also, FIG.
FIG. 3 is a diagram showing a configuration of a program (also referred to as a management unit configured by a program in the specification of the present application) which is read from the ROM 103 and written into the RAM 102 at a time;
In the figure, 201 is an application program, 2
02 denotes the file system 203 and the device driver 20
4 is the operating system that controls the FE, 203 is the FE
A file system 204 that manages the data blocks of the EPROM in the same manner as that of the hard disk drive.
e) shows a device driver that controls reading and writing of data from and to the FEEPROM using (e)).

FIG. 3 is a block diagram of the FEEPROM 1 shown in FIG.
04 shows a storage area, in which 301 is a disk area for storing a data block of a predetermined size managed by the file system 203, and 302 is the address (arbitrarily) of the data block in the rewritten disk area. An alternative page management area for storing an address block in which an allocated memory address is to be written, and an alternative page area 303 for storing an alternative block for writing a data block to be rewritten. The size of the replacement block is the same as that of the data block in the disk area, and its address corresponds to the address block in the replacement page management area 302.

As shown in FIG. 1, the hardware configuration includes a RAM 102, a ROM 103, and a FEEPROM.
104 is connected to the CPU 101 via an address bus 105 and a data bus 106;
2 includes an application program 201 and an operating system 20 stored in the ROM 103 when the power is turned on.
2. File system 203 and device driver 2
04 is stored. Further, the FEEPROM 104 is configured to be used by being divided into a disk area 301, an alternative page management area 302, and an alternative page area 303.

FIG. 4 is a flowchart showing the writing of a data block into the FEEPROM 104, and FIG.
6 is a flowchart showing data reading from the OM 104, and the operation of the present embodiment will be described with reference to FIGS. [Write to Disk Area] When writing to the disk area 301 of the FEEPROM 104, when a file write request is notified from the application program 201 to the file system 203, the file system 203 issues a file write request. Analyze, FEEPROM 104
Is notified to the device driver 204. The device driver 204, which has received the notification from the file system 203, executes writing to the FEEPROM 104 according to the flow of FIG.

That is, when there is a write request from the file system 203 to the disk area 301 (step 401), the device driver 204 first searches the alternative page management area 302 (step 402), and in the next step 403 If the address of the write request data block does not exist in the substitute page management area 302, the contents of the data block are written to the address of the disk area 301 (step 404). In step 403, the address of the write request data block is changed to the replacement page management area 30.
If the data block exists in the replacement page management area 302, the contents of the data block are written to the replacement block of the replacement page area 303 corresponding to the address block of the replacement page management area 302 (step 405).

If the writing is successful in step 406, the writing process is terminated (step 414). If the writing is in error, it is determined in step 407 whether or not the writing is to the disk area 301. If a write error occurs in the disk area 301, an unused address block in the substitute page management area 302 is searched (step 409). If a write error occurs in the substitute page area 303, the substitute page management area 30
In the address block where the address of the write request data block No. 2 has been written, a non-writable mark is written (step 408), and an unused address block in the alternative page management area 302 is searched (step 40).
9).

If there is an unused address block in the alternative page management area 302 in the next step 410,
The address of the write request data block is written to an unused address block in the alternative page management area 302 (step 412), and the alternative page area 303 corresponding to the address block in which the address of the write request data block in the alternative page management area 302 has been written. The contents of the data block are written in the alternative block (step 413). Also, in the search for an unused address block in the alternative page management area 302 performed in step 409, the replacement page management area
If an unused address block does not exist in Step 2 (Step 410), an error indicating that writing is not possible is notified to the operating system 202 by an arbitrary method.

[Read from Disk Area] FEEPRO
When reading from the disk area 301 of M104,
When a file read request is notified from the application program 201 to the file system 203, the file system 203 analyzes the file read request and
A request to read data from the disk area 301 of the EEPROM 104 is sent to the device driver 204. Device driver 204 that has been notified from the file system 203
Performs reading from the FEEPROM 104 according to the flow of FIG.

When there is a read request from the file system 203 to the disk area 301 (step 50)
1), the device driver 204 stores the alternative page management area 3
02 (step 502), and if the address of the read request data block does not exist in the substitute page management area 302 in step 503, the content of the data block is read from the address of the disk area 301 (step 504). In step 503, the alternative page management area 3
02, if the address of the read request data block exists, the content of the data block is read from the replacement block of the replacement page area 303 corresponding to the address block of the replacement page management area 302 (step 50).
5). When the reading is completed, the device driver 204
Notifies the file system 203 of the read content by an arbitrary method (step 506).

Next, an embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram for explaining a usage example of the FEEPROM 104. The FEEPROM 104 shown in FIG. 1 includes, for example, 64 8 Mbyte FEEPROMs. Therefore, the total storage capacity is 512 Mbytes. Of these, for example, 461 Mbytes are allocated to the disk area 301 (from address 00000000H (H represents hexadecimal notation) to 1 CDFFFFFH), and 100 kbytes are allocated to the alternative page management area 302 (address 1CE000
From address 00H to address 1CE18FFFH), alternative page area 3
03 has 50 MB (1FF from address 1CE19000H)
FFFFFH). In this embodiment,
The write unit per page of the FEEPROM 104 is arbitrary, and the write request block size per write from the file system is 2048 bytes.

Since writing to the substitute page area 303 is performed in units of a write request block size per one time from the file system, writing is performed in units of 2048 bytes. For example, to manage blocks in units of 2048 bytes, data block 0 starts at address 000000H and ends with 000000FFH.
00000FFF from address 00000800H for data block 1
Address H Therefore, the total number of blocks that can be replaced at the time of a write error is 25000 blocks.

In FIG. 6, data block 0 (address 00) of the disk area 301 is transmitted from the file system 203.
When a write request is issued to the address 000000H, in the processing shown in the flowchart of FIG. 4, the device driver 204 searches the contents of the address block in the alternative page management area (step 402), and
It is determined whether or not the address 00000000H of the write request data block exists in 02 (step 403). Since the address 00000000H exists in the address block 0 in the replacement page management area 302, the writing of the data block is performed to the replacement block 0 of the replacement page area 303 corresponding to the address block 0 of the replacement page management area 302. . When a write request is issued to data block 1 (address 00000800H) of the disk area 301, the data block 1 is normal and the address block 1 does not exist in the alternative page management area 302. Writing is performed to the data block 1 of 301.

When a write request is issued to data block 2 (address 00001000H) of the disk area 301, the device driver 204 determines that the data block 2 exists in the address block of the alternative page management area 302. (Step 403), and writing is performed in the replacement block 2 of the replacement page area 303. If the writing fails, the write disable mark FFFFFFFFH is written in the address block 2 of the replacement page management area 302 (step 408). ), And searches for an unused address block in the replacement page management area 302 (step 409). For example, when the address block 3 in the replacement page management area 302 is unused, the write request data is stored in this address block 3 as shown in FIG. Write block address 00001000H (step 412) Alternate page management area 30
Replacement page area 30 corresponding to address block 3 of address 2
Then, the contents of the write request data block are written into the third alternative block 3 (step 413).

In FIG. 6, the file system 20
When a read request is issued from 3 to data block 0 (address 00000000H) of the disk area 301, the device driver 204 searches the contents of the address block of the alternative page management area 302 in the processing shown in the flowchart of FIG. Then, since the address 00000000H of the read request data block exists in the address block 0 of the alternative page management area 302 (step 503), the data block is read in accordance with the address corresponding to the address block 0 of the alternative page management area 302. The processing is performed from the substitute block 0 of the page area 303 (step S50).
5). Similarly, when a read request is issued for data block 1 (address 00000800H) of the disk area 301, this data block 1 is normal and the address of this data block 1 does not exist in the alternative page management area 302. Therefore, the data is read from the data block 1 in the disk area 301.

[0029]

As described above, the method for managing a storage device using a flash memory as a storage medium according to the present invention is a disk device using the flash memory as a storage medium, and the management of the disk device is performed using a hard disk device. A special circuit is required by providing a management means having a device driver for controlling writing / reading to / from this disk device with the same interface as the file system managed in the same manner as the management of the file system and the file system of the hard disk device. Instead, it is possible to replace a storage device using a flash memory as a storage medium with a hard disk device, and change from a hard disk incorporated in the device to the storage device can be performed only by newly installing a device driver, Provide management method with high reusability at software level It can be.

Further, a disk device using a flash memory as a storage medium is composed of three areas: a disk area, an alternative page area, and an alternative page management area for writing a rewritten memory address to the alternative disk area. Thus, there is an effect that the life of the storage device can be extended.

[Brief description of the drawings]

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

FIG. 2 is a diagram for describing an embodiment of a configuration of a management unit configured by a program.

FIG. 3 is a diagram showing a storage area of a FEEPROM 104 shown in FIG.

FIG. 4 is a flowchart showing an operation of writing a data block to the FEEPROM 104;

FIG. 5 is a flowchart showing an operation of reading data from the EEPROM 104;

FIG. 6 is a diagram for explaining a usage example of the FEEPROM 104;

FIG. 7 is a diagram for explaining a first prior art.

FIG. 8 is a diagram for explaining a second prior art.

[Explanation of symbols]

101 CPU 102 RAM 103 ROM 104 Disk device (FEEPROM) using flash memory as a storage medium 105 Address bus 106 Data bus 201 Application program 202 Operating system 203 File system 204 Device driver 301 Disk area 302 Alternative page management area 303 Alternative page area S401 To S413 Operation steps indicating data block writing S501 to 506 Operation steps indicating data reading

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sotoku Kumagai 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (72) Inventor Junji Takahashi 1-403 Kosugi-cho, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Address: NEC Telecom System Corporation

Claims (7)

[Claims] 1. A storage device using a flash memory as a storage medium and a storage device storing a management unit configured by a program are connected to a CPU bus, and the management unit writes data to the storage device. In a management method of a storage device using a flash memory as a storage medium for managing read / write, the storage device is a disk device using a flash memory as a storage medium, and the management unit includes a file for managing a data block of the disk device. System, a device driver for controlling writing / reading of the disk device, an operating system for controlling the file system and the device driver, and the file system manages the management of the disk device in the same manner as the management of the hard disk device. The device driver is a hard disk drive. A flash memory comprising means for controlling writing / reading to / from the disk device through the same interface as a file system of the device, and wherein the management means manages writing / reading of data to / from the storage device. Management method of a storage device using a storage medium. 2. The interface comprises a SCSI (small
2. The management method for a storage device using a flash memory as a storage medium according to claim 1, wherein the storage device is a computer system interface. 3. The storage means according to claim 1, wherein said storage means is a ROM (or a RAM).
And a storage device using a flash memory as a storage medium. 4. A disk area for storing a data block managed by the file system with a memory address attached thereto, and rewriting when any of the data blocks in the disk area has a write failure. A replacement page area for storing a replacement block in which a data block to be written is written with the same memory address as the data block, and a replacement page management for storing an address block for writing the memory address of the data block in the rewritten disk area The device driver searches for an address block of the alternative page management area in response to a write / read request of a data block from the file system to the disk area of the disk device. Writing / reading to / from the disk area, or Management method of a storage device using a flash memory according to claim 1, wherein the managing or write / read to the serial alternative page area and the storage medium. 5. When writing a data block to the disk area when an error occurs in writing to the disk area, the device driver searches for an unused address block in an alternative page management area. If there is an unused address block, the address of the write request data block is written to the address block, and the write request data block is written to a substitute block of the substitute page area corresponding to the address block. 5. The management method for a storage device using a flash memory as a storage medium according to claim 4, wherein: 6. When writing a data block to the replacement page area and writing to the replacement page area results in an error, the disk driver sets an unused address in the replacement page management area. The block is searched, and if there is an unused address block, a write disable mark is written in the address block of the alternative page management area where the address of the write request data block was written before the search, and The address of the write request data block is written into a use address block, and the write request data block is written into a substitute block of the substitute page area corresponding to the address block. Management method for a storage device using a flash memory as a storage medium. 7. When writing a data block to the alternative page area and executing an error in writing to the alternative page area, the disk driver sets an unused address in the alternative page management area. 7. The management of a storage device using a flash memory as a storage medium according to claim 6, further comprising means for searching for a block and notifying the operating system of a write error when there is no unused address block. method.