Storage device and storing method

• US 7,757,038 B2
• Filed: 01/11/2007
• Issued: 07/13/2010
• Est. Priority Date: 10/20/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kitahara, Jun
• Primary Examiner(s): Bragdon; Reginald G
• Assistant Examiner(s): Lo; Kenneth M
• Application Number:
  US11/622,168
• Publication Number:
  US 20080098158A1
• Time in Patent Office: 1,279 Days
• Field of Search: 711/103, 711/114, 177/103, 177/114
• US Class Current: 711/103
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G11C 16/3495 Circuits or methods to detect or delay wearout of nonvolatile EPROM or EEPROM memory devices, e.g. by counting numbers of erase or reprogram cycles, by using multiple memory areas serially or cyclically
• CPC Class Codes: G11C 29/76 using address translation or modifications
• CPC Class Codes: G11C 29/765 in solid state disks

Abstract

To enable a capacity of an entire storage device to be kept by adding a flash drive or a flash module in the flash drive for a flash memory that has a failure, even if the storage device using the flash memory has a failure in its part such as a part of flash memory chip has a failure, for example, the flash memory chip has run out of its lifetime. In a storage device 101 equipped with two or more memory device units 105 with a plurality of semiconductor memory devices 107, each of which has a functional capacity unit 109 smaller than a capacity of an entire semiconductor memory device and has a writing lifetime for each functional capacity unit, only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written is substituted by a functional capacity unit in a memory device of the other memory device unit to keep a predetermined capacity of the entire device.

Claims

1. A storage device comprising:

a RAID controller unit controlling a read request and a write request from a host unit; and

a storage unit having a plurality of flash drives each flash drive comprising a drive controller and a plurality of flash memory devices in which a functional capacity unit is smaller than an entire capacity of the flash memory devices, wherein the drive controller of each flash drive determines a writing lifetime for each functional capacity unit in the flash drive,

wherein the drive controller of a first flash drive upon determining at least one functional capacity unit of the flash memory devices in which the writing lifetime exceeds a predetermined value, replaces the at least one functional capacity unit by a functional capacity unit of flash memory devices of a second flash drive, and

wherein, if the data of the at least one functional capacity unit has not been updated, the drive controller of the first flash drive controls to read data of the at least one functional capacity unit from the flash memory devices of the first flash drive in response to a read request from the host unit, and wherein the drive controller of the second flash drive controls to write data of the at least one functional capacity unit to the flash memory devices of the second flash drive in response to a write request from the host unit.

2. The storage device according to claim 1, wherein the drive controller converts between physical address information for accessing the flash memory devices and logical address information.

3. The storage device according to claim 2, wherein the drive controller manages mapping information of the physical address information and the logical address information of the flash memory devices and the RAID controller unit receives the mapping information from the drive controller.

4. The storage device according to claim 2, wherein the drive controller determines whether the flash memory device stores data corresponding to the logical address or not, and the flash memory device for reading out data is selected by the RAID controller unit based on the determination.

5. The storage device according to claim 2, wherein the first flash drive and the second flash drive are configured as a RAID group.

6. The storage device according to claim 5, wherein the drive controller stores attribute information of redundant configuration based on a writing unit in the flash memory.

7. A storing method using a storage device including a RAID controller unit controlling a read request and a write request from a host unit, and a storage unit having a plurality of flash drives each comprising a drive controller and a plurality of flash memory devices in which a functional capacity unit is smaller than an entire capacity of the flash memory devices, said storing method comprising the steps of:

determining, by the drive controller of each flash drive, a writing lifetime for each functional capacity unit in the flash drive;

upon the drive controller of a first flash drive upon determining at least one functional capacity unit of the flash memory devices in which the writing lifetime exceeds a predetermined value, replacing the at least one functional capacity unit by a functional capacity unit of flash memory devices of a second flash drive, and

controlling, by the drive controller of the first flash drive if the data of the at least one functional capacity unit has not been updated, to read data of the at least one functional capacity unit from the flash memory devices of the first flash drive in response to a read request from the host unit; and

controlling, by the drive controller of the second flash drive, to write data of the at least one functional capacity unit to the flash memory devices of the second flash drive in response to a write request from the host unit.

8. A storing method according to claim 7, wherein the drive controller converts between physical address information for accessing the semiconductor memory device and logical address information.

9. A storing method according to claim 8, wherein the drive controller manages mapping information of the physical address information and the logical address information of the flash memory devices and the RAID controller unit receives the mapping information from the drive controller.

10. The storing method according to claim 8, wherein the drive controller determines whether the flash memory device stores data corresponding to the logical address or not and the flash memory device for reading out data is selected based on the determination.

11. The storing method according to claim 8, wherein the first flash drive and the second flash drive are configured as a RAID group.

12. The storing method according to claim 11, wherein the drive controller stores attribute information of redundant configuration based on a writing unit in the flash memory.