METHOD AND SYSTEM FOR MANAGING WEAR-LEVEL AWARE FILE SYSTEMS

• US 20090327602A1
• Filed: 06/30/2008
• Published: 12/31/2009
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Johnson, Darrin P., Moore, William H., Saxe, Eric C.
• Granted Patent: US 8,135,907 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0634 by changing the state or mode of one or more devices
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays

Abstract

A method for wear level-based allocation in a storage pool. The method includes receiving a first request to write a first data item in a storage pool, where the storage pool includes a number of physical locations associated with the storage devices, and where each of the storage devices includes metadata regarding a level of wear of the storage device. The method further includes determining a first target physical location selected from the plurality of physical locations by using a wear-level selection policy and a wear cost for each of the storage devices, where the wear cost is determined based on a type of the storage device. The method further includes allocating a first data block to the first target physical location writing the first data block to the first target physical locations, wherein the first data block comprises a first portion of the first data item.

Claims

1. A method for wear level-based allocation in a storage pool, comprising:

receiving a first request to write a first data item in a storage pool,

wherein the storage pool comprises a plurality of storage devices and a plurality of physical locations associated with the storage devices, and

wherein each of the plurality of storage devices comprises metadata regarding a level of wear of the storage device;

determining a first target physical location selected from the plurality of physical locations by using a wear-level selection policy and a wear cost for each of the storage devices, wherein the wear cost is determined based on a type of the storage device;

allocating a first data block to the first target physical location; and

writing the first data block to the first target physical locations, wherein the first data block comprises a first portion of the first data item.

2. The method of claim 1 further comprising:

determining a second target physical location from the plurality of physical locations by using the wear-level selection policy and wear cost for each of the storage devices;

allocating a second block to the second target physical location; and

writing the second block to the second target physical location, wherein the second block comprises a second portion of the first data item.

4. The method of claim 1, wherein each of the storage devices is one selected from the group of a hard disk, a flash-type disk, and a hybrid disk.

5. The method of claim 1, wherein the wear cost for the storage device is a function of at least one selected from a group consisting of spinning-up one of the plurality of storage devices, spinning-up down one of the plurality of storage devices, writing to one of the plurality of storage devices and reading from one of the plurality of storage devices.

6. The method of claim 1, wherein the level of wear of the storage device comprises at least one selected from a group consisting of a number of write operations per cell in the storage device, a number read operations per cell in the storage device, a number of time the storage device has been spun-up, and a number of times the storage device has been spun-down.

7. The method of claim 6, wherein the metadata comprises a threshold wear level corresponding to a wear level at which the storage device is no longer selected for allocation.

3. The method of clam 1, wherein the wear-level policy is defined to extended the lifetime of the storage devices.

8. A method for retrieving a logical block, comprising:

receiving a request to read the logical block;

obtaining metadata associated with the logical block, wherein the metadata comprises;

a replication type used to store the logical block;

physical block locations in a storage pool for each physical block associated with the logical block, wherein each physical block location specifies one of a plurality of storage devices in the storage pool;

obtaining wear-level information comprising a level of wear for each of the storage devices specified in the physical block locations;

selecting a first set of physical block locations using the metadata, the wear-level information, and a wear-level selection policy;

generating a first set of I/O requests, wherein each I/O request specifies one of the first set of physical block locations;

issuing a first set of I/O requests;

receiving the first set of physical blocks in response to the first set of I/O requests; and

constructing the logical block using the first set of physical blocks.

9. The method of claim 8, further comprising:

after constructing the logical block, calculating a checksum of the logical block;

comparing the checksum to a stored checksum of the logical block, wherein the checksum and stored checksum do not match;

selecting a second set of physical block locations using the metadata, the wear-level information, and the wear-level selection policy;

generating a second set of I/O requests, wherein each I/O request specifies one of the second set of physical block locations;

issuing the second set of I/O requests;

receiving the second set of physical blocks in response to the second set of I/O requests; and

constructing the logical block using the second set of physical blocks.

10. The method of claim 8, wherein the replication type defines a level of replication of the logical block in the storage pool.

11. The method of claim 10, wherein the replication type is one selected from a group consisting of 2-way mirroring, n-way mirroring, and RAID-type replication.

12. The method of claim 8, wherein the level of wear for each of the storage device comprises at least one selected from a group consisting of a number of write operations per cell in the storage device, a number read operations per cell in the storage device, a number of time the storage device has been spun-up, and a number of times the storage device has been spun-down.

13. The method of claim 8, wherein selecting the first set of physical locations comprises:

selecting the first set of physical block locations, wherein the physical blocks at the first set of physical block locations combine to form the logical block;

determining a first wear cost to obtain the physical block locations located at the first set of physical block locations using the wear-level information;

selecting a second set of physical block locations, wherein the physical blocks at the second set of physical block locations combine to form the logical block;

determining a second wear cost to obtain the physical blocks located at the second set of physical block locations using the wear-level information;

selecting the first set of physical block locations using the first wear cost, the second wear cost, and the wear-level selection policy; and

determining a first set of wear-level distribution Input/Output (I/O) queues using the first set of physical block locations.

14. The method of claim 13, wherein each of the wear-level distribution I/O queues is associated with one of the plurality of storage devices.

15. The method of claim 8, wherein the wear-level information comprises a threshold wear level corresponding to a wear level at which the storage device is determined to be no longer selected for allocation.

16. A computer readable medium comprising a plurality of executable instructions for, retrieving a logical block, wherein the plurality of executable instructions comprises instructions to:

receive a request to read the logical block;

obtain metadata associated with the logical block, wherein the metadata comprises;

a replication type used to store the logical block;

physical block locations in a storage pool for each physical block associated with the logical block, wherein each physical block location specifies one of a plurality of storage devices in the storage pool;

obtain wear-level information comprising a level of wear for each of the storage devices specified in the physical block locations;

select a first set of physical block locations using the metadata, the wear-level information, and a wear-level selection policy;

generate a first set of I/O requests, wherein each I/O request specifies one of the first set of physical block locations;

issue a first set of I/O requests;

receive the first set of physical blocks in response to the first set of I/O requests; and

construct the logical block using the first set of physical blocks.

17. The computer readable medium of claim 16, wherein the plurality of executable instructions further comprises instructions to:

after constructing the logical block, calculating a checksum of the logical block;

compare the checksum to a stored checksum of the logical block, wherein the checksum and stored checksum do not match;

select a second set of physical block locations using the metadata, the wear-level information, and the wear-level selection policy;

generate a second set of I/O requests, wherein each I/O request specifies one of the second set of physical block locations;

issue the second set of I/O requests;

receive the second set of physical blocks in response to the second set of I/O requests; and

construct the logical block using the second set of physical blocks.

18. The computer readable medium of claim 16, wherein the replication type defines a level of replication of the logical block in the storage pool.

19. The computer readable medium of claim 18, wherein the replication type is one selected from a group consisting of 2-way mirroring, n-way mirroring, and RAID-type replication.

20. The computer readable medium of claim 16, wherein the level of wear for each of the storage device comprises at least one selected from a group consisting of a number of write operations per cell in the storage device, a number read operations per cell in the storage device, a number of time the storage device has been spun-up, and a number of times the storage device has been spun-down.