Flash memory storage system

• US 20070283079A1
• Filed: 08/14/2006
• Published: 12/06/2007
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kawamura, Shunji, Fujimoto, Kazuhisa, Iwamura, Takashige, Eguchi, Yoshiaki
• Granted Patent: US 7,640,390 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A flash memory storage system has a plurality of flash memory devices comprising a plurality of flash memories, and a controller having an I/O processing control unit for accessing a flash memory device specified by a designated access destination in an I/O request received from an external device from among the plurality of flash memory devices. A parity group can be configured of flash memory devices having identical internal configuration.

Claims

1. A flash memory storage system for receiving and processing an I/O request from an external device, comprising:

a plurality of flash memory devices (FMD) comprising a plurality of flash memories; and

a controller having an I/O processing control unit for accessing an FMD specified by a designated access destination in said received I/O request, from among said plurality of FMD.

2. The flash memory storage system according to claim 1, wherein

two or more parity groups configured of two or more FMD from among said plurality of FMD are present;

FMD with different internal configurations are contained in said plurality of FMD; and

each parity group is configured of FMD with identical internal configuration.

3. The flash memory storage system according to claim 2, wherein

said internal configuration is at least one from among (1) through (3) below:

(1) the number of flash memories provided in the FMD;

(2) a block size employed by the FMD;

(3) the total storage capacity of a plurality of flash memories provided in the FMD.

4. The flash memory storage system according to claim 2, wherein

a plurality of FMD types including at least one FMD type from among a first type, a second type, and a third type are present as said internal configuration;

a first FMD, which is an FMD of said first FMD type, comprises;

a plurality of flash memories; and

an internal controller having a first FMD control unit for controlling input and output to and from said plurality of flash memories, wherein when said FMD is said first FMD, said first FMD control unit controls said input and output according to an access from said I/O processing control unit,

a second FMD, which is an FMD of said second FMD type, comprises;

a plurality of said first FMD; and

a second FMD control unit for controlling access to said plurality of first FMD according to an access from said I/O processing control unit, wherein each of said plurality of first FMD is recognized by said controller, said first FMD control unit of each first FMD controls said input and output according to an access from said second FMD control unit, and

a third FMD, which is an FMD of said third type, comprises;

a plurality of said first FMD; and

a third FMD control unit for controlling access to said plurality of first FMD according to an access from said I/O processing control unit, said plurality of FMD are recognized as one device by said controller, and said first FMD control unit of each first FMD controls said input and output according to an access from said third FMD control unit.

5. The flash memory storage system according to claim 4, wherein said internal configuration further demonstrates at least one performance from among those of said internal controller, said second FMD control unit, and said third FMD control unit.

6. The flash memory storage system according to claim 1, wherein an FMD that differs by a vendor and/or production data is included in said plurality of FMD.

7. The flash memory storage system according to claim 2, wherein one or a plurality of disk-type storage devices are present in addition to said plurality of FMD, but none of said one or a plurality of disk-type storage devices is present in said parity group comprising said FMD.

8. The flash memory storage system according to claim 1, wherein

each FMD detects insufficiency of free storage capacity thereof and further comprises an information notification unit for sending a predetermined message when said insufficiency is detected, and

said controller executes control in response to said predetermined message.

9. The flash memory storage system according to claim 2, wherein

said controller further comprises a configuration control unit;

and

when said configuration control unit detects that any one FMD from among said plurality of FMD has been blocked, the configuration control unit specifies a parity group to which said blocked FMD belongs, searches for another FMD compatible with said parity group, recovers data located in said blocked FMD, and writes said recovered data into the found other FMD.

10. The flash memory storage system according to claim 1, wherein

at least one of said two or more parity groups is configured of two or more second FMD,

said second FMD comprises:

a plurality of first FMD; and

a second FMD control unit for controlling access to said plurality of first FMD according to an access from said I/O processing control unit, wherein each of said plurality of first FMD is recognized by said controller,

said first FMD comprises;

a plurality of flash memories; and

an internal controller having a first FMD control unit for controlling input to and output from said plurality of flash memories, wherein said first FMD control unit of each first FMD controls said input and output according to the access from said second FMD control unit.

11. The flash memory storage system according to claim 10, wherein

said controller manages the presence and absence of a failure in the first FMD units with respect to a parity group configured of said two or more second FMD.

12. The flash memory storage system according to claim 10, wherein

the parity group configured of said two or more second FMD comprises a plurality of sub-parity groups;

each sub-parity group is configured of two or more first FMD in at least one of said two or more second FMD;

at least one logical storage unit is provided by said each sub-parity group; and

even when data present in a sub-parity group from among said plurality of sub-parity groups cannot be restored, if another sub-parity group in which no failure has occurred is present from among said plurality of sub-parity groups, the I/O processing control unit performs input and output, without blocking a storage unit present on said other sub-parity group.

13. The flash memory storage system according to claim 10, wherein

the parity group configured of said two or more second FMD comprises a plurality of sub-parity groups;

and

each sub-parity group is configured of first FMD present in respectively different second FMD from among said two or more second FMD.

14. The flash memory storage system according to claim 10, wherein

a spare first FMD that does not belong to a parity group is provided in at least one second FMD;

said controller comprises a configuration control unit; and

when a need has arisen in a certain second FMD, said configuration control unit uses said spare first FMD present in said second FMD.

15. The flash memory storage system according to claim 14, wherein

when said spare first FMD is not present in said second FMD where a need has arisen, said configuration control unit uses said spare first FMD present in another second FMD.

16. The flash memory storage system according to claim 14, wherein

when said spare first FMD is not present in said second FMD where a need has arisen, said configuration control unit searches a separate second FMD compatible with a parity group to which said second FMD belongs, writes data present in said second FMD into said separate second FMD, and blocks said second FMD.

17. The flash memory storage system according to claim 1, wherein

said controller comprises a configuration control unit;

and

said configuration control unit checks whether or not the internal configurations of a plurality of FMD designated from said external device as configuration elements of a parity group are identical and outputs an alarm to said external device when the internal configurations are not identical.

18. The flash memory storage system according to claim 1, wherein

a plurality of logical storage units are provided by said plurality of FMD and a block size of each storage unit is less than a block size of each FMD.

19. The flash memory storage system according to claim 1, further comprises a cache memory, wherein

when said I/O request is a read request, said I/O processing control unit reads data from said plurality of FMD according to said read request, temporarily accumulates the data that have been read out in said cache memory, then sends the data accumulated in said cache memory to said external device, and checks the correctness of data that are accumulated in said cache memory when said data that have been read out are accumulated in said cache memory.

20. The flash memory storage system according to claim 1, wherein

a plurality of address spaces are hierarchized, block sizes in each layer are different, and

a flash memory, an FMD, a parity group configured of two or more FMD, and a logical storage unit to be provided to said external device are present as a layer.