STORAGE DEVICE AND STORING METHOD

• US 20080098158A1
• Filed: 01/11/2007
• Published: 04/24/2008
• Est. Priority Date: 10/20/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: KITAHARA, Jun
• Granted Patent: US 7,757,038 B2
• Time in Patent Office: Days
• 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 with a functional capacity unit smaller than an entire capacity of semiconductor memory devices and equipped with two or more memory device units with a plurality of semiconductor memory devices, each of the semiconductor memory devices has a writing lifetime for each functional capacity unit, wherein

only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory device unit is substituted by a functional capacity unit in a semiconductor memory device of another memory device unit to keep a predetermined capacity of the entire device.

2. The storage device according to claim 1, wherein the memory device unit is a memory module formed by a plurality of semiconductor memory devices, each of which has a functional capacity unit smaller than an entire capacity of semiconductor memory devices and has a writing lifetime for each functional capacity unit, and a memory controller with a function for converting physical address information for accessing the semiconductor memory device and logical address information, wherein only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory module is substituted by a functional capacity unit in a semiconductor memory device of another memory module.

3. The storage device according to claim 1, wherein the memory device unit is a drive formed by a plurality of memory modules, each of which is formed by a plurality of semiconductor memory devices, each of which has a functional capacity unit smaller than an entire capacity of semiconductor memory devices and has a writing lifetime for each functional capacity unit, and a memory controller with a function for converting physical address information for accessing the semiconductor memory device and logical address information;

and a drive controller with a function for converting physical address information for accessing the semiconductor memory device of the memory module and logical address information, wherein only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory module of a drive is substituted by a functional capacity unit in a semiconductor memory device of a memory module of another drive.

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

5. The storage device according to claim 2, wherein a writing unit is selected from a semiconductor memory device of a plurality of memory device units one by one, the plurality of writing units forming a redundant configuration, and wherein the memory controller or the drive controller of the memory device unit returns information on whether it can accept a writing request or not, and a semiconductor memory device of the memory device unit that can address the writing is selected based on the returned information.

6. The storage device according to claim 2, wherein a writing unit is selected from a semiconductor memory device of a plurality of memory device units one by one, the plurality of writing units forming a redundant configuration, and wherein the memory controller or the drive controller writes additional information including an order of the pieces of data, kinds of data such as a parity and an arrangement of the pieces of data at a time when the redundant configuration is taken, and correct data is restored based on the additional information when the writing units are read out.

7. The storage device according to claim 2, wherein the memory controller or the drive controller keeps information on relationship with a logical address for each of the functional capacity unit of the semiconductor memory device and creates information on relationship with an added logical address of an added semiconductor memory device when the semiconductor memory device is added.

8. A storing method using a storage device equipped with two or more memory device units with a plurality of semiconductor memory devices, each of which has a functional capacity unit smaller than an entire capacity of semiconductor memory devices and has a writing lifetime for each functional capacity unit, comprising a step of:

storing only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory device unit by substituting the functional capacity unit by a functional capacity unit in a semiconductor memory device of another memory device unit to keep a predetermined capacity of the entire device.

9. A storing method according to claim 8, wherein the memory device unit is a memory module formed by a plurality of semiconductor memory devices, each of which has a functional capacity unit smaller than an entire capacity of semiconductor memory devices and has a writing lifetime for each functional capacity unit, and a memory controller with a function for converting physical address information for accessing the semiconductor memory device and logical address information, comprising a step of storing only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory module by substituting the functional capacity unit by a functional capacity unit in a semiconductor memory device of another memory module.

10. A storing method according to claim 8, wherein the memory device unit is a drive formed by a plurality of memory modules, each of which is formed by a plurality of semiconductor memory devices, each of which has a functional capacity unit smaller than an entire capacity of semiconductor memory devices and has a writing lifetime for each functional capacity unit, and a memory controller with a function for converting physical address information for accessing the semiconductor memory device and logical address information;

and a drive controller with a function for converting physical address information for accessing the semiconductor memory device of the memory module and logical address information, wherein only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written in a semiconductor memory device of a memory module by substituting the functional capacity unit by a functional capacity unit in a semiconductor memory device of another memory module.

11. The storing method according to claim 8, further comprising the steps of:

giving a logical address to a semiconductor memory device of the memory device unit;

determining whether the semiconductor memory device of the memory device unit stores data corresponding to the logical address or not; and

selecting the semiconductor memory device of the memory device unit for reading out data based on the determination.

12. The storing method according to claim 8, further comprising the steps of:

selecting writing units from a plurality of semiconductor memory devices one by one, with the plurality of writing units forming a redundant configuration;

returning information on whether the memory device unit accepts a writing request or not; and

selecting the semiconductor memory device of the memory device unit that can address writing based on the returned information.

13. The storing method according to claim 8, further comprising the steps of:

selecting writing units from a semiconductor memory device of a plurality of memory device units one by one, with the plurality of writing units forming a redundant configuration;

writing additional information including an order of the pieces of data, kinds of data such as a parity and an arrangement of the pieces of data at a time when the redundant configuration is taken; and

restoring correct data based on the additional information when the writing units are read out.

14. The storing method according to claim 8, comprising the steps of:

saving information on relationship with a logical address for each functional capacity unit of the semiconductor memory device; and

creating information on relationship with an added logical address of an added semiconductor memory device when the semiconductor memory device is added.