JP2010146220A - Semiconductor disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor disk drive that includes a plurality of flash memories in a semiconductor disk drive and replaces the flash memory to be used according to the number of writes, thus extending the life of the semiconductor disk drive. <P>SOLUTION: The semiconductor disk drive includes: a plurality of flash memory devices which are independently accessible; a control part 11 which performs access control to the flash memory devices; and a management table 12 which manages the number of writes to the flash memory devices. When the number of writes to the flash memory devices reaches a preset threshold, data is copied to a spare flash memory device and the operations are continued. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor disk drive using a flash memory, and has a plurality of independent flash memory devices, a control circuit for the flash memory device, and a management table for managing the number of writes to the flash memory device. When the set number of times is reached, the flash memory device to be used is replaced, thereby extending the life of the semiconductor disk drive itself.

  In recent years, a semiconductor disk drive using a flash memory as a substitute for a hard disk drive has attracted attention due to an increase in demand for power saving of server devices.

  The semiconductor disk drive has the advantages of low power consumption, no mechanical drive part and low failure rate, but on the other hand, the number of writes is limited due to the characteristics of flash memory, and a system that writes frequently. However, there is a disadvantage that the life is shorter than the hard disk drive.

  With regard to such disadvantages, in Japanese Patent Laid-Open No. 2008-9594 “Semiconductor memory device management system, semiconductor memory device, host device, program, semiconductor memory device management method”, the lifetime is predicted from the number of times the semiconductor memory device is written. A means for notifying the user has been proposed, but it does not extend the life of the semiconductor memory device itself.

JP 2008-9594 A

  The problem to be solved is that the flash memory used for the semiconductor disk drive has a limited number of times of writing, and the service life of the semiconductor disk drive itself is shorter than that of the server device on which the semiconductor disk drive is mounted.

  The most important aspect of the present invention is to provide a semiconductor disk drive with a plurality of independent flash memory devices, replace the flash memory device to be used according to the number of writes, and replace the flash memory that has become unusable during operation. Features.

  The semiconductor disk drive according to the present invention includes a plurality of flash memories. The flash memory to be used is replaced according to the number of times of writing, and the flash memory that has become unusable is replaced during operation, thereby extending the life of the semiconductor disk drive. There is an advantage to prolong.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of the present invention.

  The semiconductor disk drive 10 is connected to the CPU 30 by an interface 31. Although not shown, the CPU 30 is a system composed of a processor, a memory, and an I / O device. The semiconductor disk drive 10 is one of the I / O devices of the CPU 30.

  The semiconductor disk drive 10 includes an access control unit 11 and flash memory devices 20 and 21. Flash memory devices 20 and 21 are replaceable during operation.

  The access control unit 11 includes an access management table 12 and manages “usage state”, “write count”, and “exchange threshold” for each of the semiconductor disks 20 and 21, as shown in FIG. Also, as shown in FIG. 3, the usage state includes “00” meaning “not used”, “01” meaning “used”, “10” meaning “data migration”, and “11” meaning “unusable”. There are four states.

  Next, the operation of the embodiment will be described.

  FIG. 4 is a flowchart illustrating the read operation.

  First, the semiconductor disk drive 10 receives a read request from the CPU 30 through the interface 31 (step 401). The access control unit 11 that has received the read request refers to the access management table 12 (step 402) and checks the usage state of the flash memory device (step 403). If the state of either the flash memory device 20 or 21 is “01 (in use)”, data is read from the corresponding flash memory device (step 404), and read data is returned to the CPU 30 (step 405).

  If the status of the flash memory device is “10 (data migration)”, the status check is repeated until the status becomes “01 (in use)” (step 406).

  If the status of the flash memory device is neither “01 (in use)” nor “10 (data migration)”, it is determined that there is no readable device, and an error is returned to the CPU 30 (step 407).

  5 and 6 are flowcharts for explaining the write operation.

  First, the semiconductor disk drive 10 receives a write request from the CPU 30 through the interface 31 (step 501). The access control unit 11 that has received the write request refers to the access management table 12 (step 502) and checks the state of the flash memory device (step 503).

  If the state is “01 (in use)”, the corresponding flash memory device is written (step 504). If the status is “10 (data migration in progress)”, the status check is repeated until the status becomes “01 (in use)” (step 507).

  If the status of the flash memory device is neither “01 (in use)” nor “10 (data migration)”, it is determined that there is no writable device, and an error is returned to the CPU 30 (step 508). ).

  After writing is completed in step 504, 1 is added to the number of writes of the flash memory device that has written (step 505), and the number of writes and the replacement threshold are compared (step 506).

  If the write count exceeds the replacement threshold, the access control unit changes the status of the flash memory device currently in use to “10 (data migration)” (step 601), and the data in the flash memory device in use Is copied to a spare flash memory device (step 602). When copying is completed, the status of the flash memory device currently in use is set to “11 (unusable)” (step 603), and the status of the spare flash memory device is set to “01 (in use)” (step 604).

  Here, the flash memory device that has become “11 (unusable)” becomes a spare flash memory device because the status becomes “00 (unused)” by replacement during operation.

  As described above, according to the present invention, a plurality of flash memories are provided, the flash memory to be used is replaced according to the number of times of writing, and the flash memory that has become unusable is replaced during operation. There is an advantage of extending the service life semipermanently.

It is a block diagram which shows one Example of this invention. It is explanatory drawing of the access management table in one Example of this invention. It is a list of the use state flag in one Example of this invention. 6 is a flowchart illustrating a read operation in an embodiment of the present invention. It is a flowchart explaining the write operation in one Example of this invention. It is a flowchart explaining the write operation in one Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Semiconductor disk drive, 11 ... Access control part, 12 ... Access management table, 20 ... Flash memory device, 21 ... Flash memory device, 30 ... CPU, 31 ... Interface.

Claims (2)

  In a semiconductor disk drive using flash memory, a plurality of flash memory devices that can be accessed independently, a control unit that controls access to the flash memory device, and management that manages the number of writes to the flash memory device A semiconductor disk drive comprising a table, wherein when a write count to a flash memory device reaches a preset threshold, data is copied to a replacement flash memory device and the operation is continued.   2. The semiconductor disk drive according to claim 1, wherein the flash memory device portion can be replaced while the semiconductor disk drive is in operation.

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