DATA CONTROL APPARATUS, STORAGE SYSTEM, AND COMPUTER PROGRAM PRODUCT

• US 20100005228A1
• Filed: 02/26/2009
• Published: 01/07/2010
• Est. Priority Date: 07/07/2008
• Status: Active Grant

• Current Assignee: Toshiba Memory Corporation (Kioxia Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: SATO, Hideaki, FUKUTOMI, Kazuhiro, ASANO, Shigehiro, KANNO, Shinichi
• Granted Patent: US 8,069,301 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 2212/7211 Wear leveling

Abstract

A data control apparatus includes a mapping-table managing unit that manages a mapping table that is associated with a corrupted-data recovery function of recording data and error correcting code data as redundant data that is given separately from the data, distributed and stored in units of stripe blocks in the plural nonvolatile semiconductor memory devices, the mapping table containing arrangement information of the data and the error correcting code data; a determining unit that determines whether to differentiate frequencies of writing the data into the semiconductor memory devices; and a changing unit that changes the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table to differentiate the frequencies of writing the data into the semiconductor memory devices, when the determining unit determines that the frequencies of writing the data into the semiconductor memory devices are to be differentiated.

Claims

1. A data control apparatus comprising:

a mapping-table managing unit that manages a mapping table that is contained arrangement information of data and error correcting code data as redundant data that is given separately from the data, distributed and stored in units of stripe blocks in the plural nonvolatile semiconductor memory devices;

a determining unit that determines whether to differentiate frequencies of writing the data into the semiconductor memory devices; and

a changing unit that changes the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table to differentiate the frequencies of writing the data into the semiconductor memory devices, when the determining unit determines that the frequencies of writing the data into the semiconductor memory devices are to be differentiated.

2. The apparatus according to claim 1, further comprising:

a writing-frequency managing unit that manages information about the frequency of writing of each of the stripe blocks; and

a life-information managing unit that manages information about residual lives of the semiconductor memory devices, wherein

the determining unit determines whether to differentiate the frequencies of writing the data into the semiconductor memory devices, based on the information about the frequency of writing of each of the stripe blocks, the information about the residual lives of the semiconductor memory devices, and information about the frequencies of writing into the semiconductor memory devices that can be calculated from the mapping table and the information about the frequency of writing of each of the stripe blocks.

3. The apparatus according to claim 1, wherein the changing unit changes the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table, and switches the data stored in units of the stripe blocks, to differentiate the frequencies of writing the data into the semiconductor memory devices in a stepwise manner.

4. The apparatus according to claim 3, wherein the changing unit changes the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table to smooth the frequencies of writing the data into the semiconductor memory devices, when a certain period of time has elapsed since the frequencies of writing the data into the semiconductor memory devices are differentiated.

5. The apparatus according to claim 1, wherein when a difference in life expectancy between top two of the semiconductor memory devices having shorter life expectancies becomes lower than a predetermined threshold value, the changing unit changes the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table to differentiate the frequencies of writing into the top two semiconductor memory devices having shorter life expectancies.

6. The apparatus according to claim 5, wherein the changing unit allocates a higher writing frequency to the semiconductor memory device having a shorter life expectancy.

7. The apparatus according to claim 1, wherein the changing unit only allows switching within one and the same stripe group to maintain a fault tolerant configuration as restrictions of the determination of stripe block switching.

8. The apparatus according to claim 1, wherein the changing unit only allows switching of the stripe blocks within one and the same semiconductor memory device to maintain a fault tolerant configuration as restrictions of the determination of stripe block switching.

9. The apparatus according to claim 1, wherein the changing unit uses a swap space in the switching of data stored in units of the stripe blocks.

10. The apparatus according to claim 1 wherein the changing unit uses a recovery function of redundant arrays of independent/inexpensive disks (RAID) in the switching of data stored in units in the stripe blocks.

11. A storage system comprising:

plural nonvolatile semiconductor memory devices; and

the data control apparatus according to one of claims 1 to 10.

12. A computer program product having a computer readable medium including programmed instructions for controlling data, wherein the instructions, when executed by a computer, cause the computer to perform:

managing a mapping table that is contained arrangement information of data and error correcting code data as redundant data that is given separately from the data, distributed and stored in units of stripe blocks in the plural nonvolatile semiconductor memory devices;

determining whether to differentiate frequencies of writing the data into the semiconductor memory devices; and

changing the arrangement information by switching the data stored in units of the stripe blocks managed using the mapping table to differentiate the frequencies of writing the data into the semiconductor memory devices, when it is determined that the frequencies of writing the data into the semiconductor memory devices are to be differentiated.