Host I/O performance and availability of a storage array during rebuild by prioritizing I/O request

• US 6,647,514 B1
• Filed: 03/23/2000
• Issued: 11/11/2003
• Est. Priority Date: 03/23/2000
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Umberger, David K., Daniels, Rodger D., Belhadj, Mohamed
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): Maskulinski, Michael
• Application Number:
  US09/534,921
• Time in Patent Office: 1,328 Days
• Field of Search: 714/42, 714/6, 714/747, 714/22, 714/5-7, 711/114, 711/162, 358/450, 365/228
• US Class Current: 714/42
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk

Abstract

Improved host I/O performance and availability of a storage array during rebuild is obtained by prioritizing I/O requests. In one embodiment, rebuild I/O requests are given priority over host I/O requests when the storage array is close to permanently losing data (for example, failure of one more particular disk in the storage array would result in data loss). Rebuild I/O requests continue to have priority over host I/O requests until the storage array is no longer close to permanently losing data, at which point host I/O requests are given priority over rebuild I/O requests.

Claims

1. A method comprising:

identifying that a storage array is close to permanently losing data, wherein the storage array and a corresponding controller include a plurality of resources; and

giving, in response to identifying that the storage array is close to permanently losing data, input/output (I/O) requests for rebuilding at least a portion of the storage array priority over host I/O requests, and wherein giving I/O requests for rebuilding at least a portion of the storage array priority over host I/O requests comprises restricting host I/O resource usage to not exceed a threshold amount.

2. A method as recited in claim 1, wherein the threshold amount is user-configurable.

3. A method as recited in claim 1, wherein:

the storage army comprises a redundant array of independent disks (RAID) system that includes a plurality of RAID levels;

the identifying comprises identifying when at least one of the plurality of RAID levels is close to permanently losing data; and

the giving comprises giving rebuild I/O requests priority over host I/O requests only for the at least one RAID level that is close to permanently losing data.

4. One or more computer-readable media having stored thereon a computer program that, when executed by one or more processors of a computer, causes the one or more processors to perform acts including:

identifying that a storage array is close to permanently losing data, wherein the storage array and a corresponding controller include a plurality of resources; and

giving, in response to identifying that the storage array is close to permanently losing data, input/output (I/O) requests for rebuilding at least a portion of the storage array priority over host I/O requests, and wherein giving I/O requests for rebuilding at least a portion of the storage array priority over host I/O requests comprises restricting host I/O resource usage to not exceed a threshold amount.

5. One or more computer-readable media as recited in claim 4, wherein:

the storage array comprises a redundant array of independent disks (RAID) system that includes a plurality of RAID levels;

the identifying comprises identifying when at least one of the plurality of RAID levels is close to permanently losing data; and

the giving comprises giving rebuild I/O requests priority over host I/O requests only for the at least one RAID level that is close to permanently losing data.

6. An apparatus comprising:

a priority identifier to determine whether host input/output (I/O) requests or rebuild I/O requests for a storage array are to have priority, wherein the storage array comprises a redundant array of independent disks (RAID) system, wherein the RAID system includes a plurality of RAID levels; and

a request dispatcher, communicatively coupled to the priority identifier, to select host I/O requests and rebuild I/O requests for execution based at least in part on whether host I/O requests or rebuild I/O requests are to have priority,

wherein the apparatus further comprises,

a priority identifier associated with each of the plurality of RAID levels, and

a request dispatcher associated with each of the plurality of RAID levels.