Method and system for managing wear-level aware file systems

• US 8,135,907 B2
• Filed: 06/30/2008
• Issued: 03/13/2012
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Oracle America, Inc. (Oracle Corporation)
• Inventors: Moore, William H., Johnson, Darrin P., Saxe, Eric C.
• Primary Examiner(s): Shah, Sanjiv
• Assistant Examiner(s): TSUI, DANIEL D
• Application Number:
  US12/165,463
• Publication Number:
  US 20090327602A1
• Time in Patent Office: 1,352 Days
• Field of Search: None
• 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 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;

selecting a first set of physical block locations using a wear-level selection policy, wherein selecting the first set of physical locations comprises;

identifying the first set of physical block locations using the metadata, wherein the physical blocks at the first set of physical block locations combine to form the logical block,

determining a wear cost to read each of the physical blocks located at the first set of physical block locations to obtain a first plurality of wear costs,

combining the first plurality of wear costs to obtain a first aggregate wear cost,

identifying a second set of physical block locations using the metadata, wherein the physical blocks at the second set of physical block locations combine to form the logical block,

determining a wear cost to read each of the physical blocks located at the second set of physical block locations to obtain a second plurality of wear costs,

combining the second plurality of wear costs to obtain a second aggregate wear cost, and

selecting the first set of physical block locations based on the first aggregate wear cost, the second aggregate wear cost, and the 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.

2. The method of claim 1, 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, based on the comparing, the second set of physical block locations;

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.

3. The method of claim 1, wherein the replication type defines a level of replication of the logical block in the storage pool.

4. The method of claim 3, wherein the replication type is one selected from a group consisting of 2-way mirroring, n-way mirroring, and RAID-type replication.

5. The method of claim 1, wherein selecting the first set of physical block locations further comprises determining a first set of wear-level distribution Input/Output I/O) queues using the first set of physical block locations, wherein each of the wear-level distribution I/O queues is associated with one of the plurality of storage devices.

6. A non-transitory 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;

select a first set of physical block locations using a wear-level selection policy, wherein selecting the first set of physical locations comprises;

identifying the first set of physical block locations using the metadata, wherein the physical blocks at the first set of physical block locations combine to form the logical block,

determining a wear cost to read each of the physical blocks located at the first set of physical block locations to obtain a first plurality of wear costs,

combining the first plurality of wear costs to obtain a first aggregate wear cost,

identifying a second set of physical block locations using the metadata, wherein the physical blocks at the second set of physical block locations combine to form the logical block,

determining a wear cost to read each of the physical blocks located at the second set of physical block locations to obtain a second plurality of wear costs,

combining the second plurality of wear costs to obtain a second aggregate wear cost, and

selecting the first set of physical block locations based on the first aggregate wear cost, the second aggregate wear cost, and the 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.

7. The non-transitory computer readable medium of claim 6, 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, based on the comparing, the second set of physical block locations;

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.

8. The non-transitory computer readable medium of claim 6, wherein the replication type defines a level of replication of the logical block in the storage pool.

9. The non-transitory computer readable medium of claim 8, wherein the replication type is one selected from a group consisting of 2-way mirroring, n-way mirroring, and RAID-type replication.