Simplified parity disk generation in a redundant array of inexpensive disks

• US 20070294565A1
• Filed: 04/28/2006
• Published: 12/20/2007
• Est. Priority Date: 04/28/2006
• Status: Abandoned Application

• Current Assignee: NetApp, Inc.
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Saxena, Pawan, Stager, Roger, Johnston, Craig
• Application Number:
  US11/413,325
• Publication Number:
  US 20070294565A1
• Time in Patent Office: Days
• US Class Current: 714/6.12
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1061 Parity-single bit-RAID4, i.e. RAID 4 implementations

Abstract

A method for efficiently writing data to a redundant array of inexpensive disks (RAID) includes: writing an entire slice to the RAID at one time, wherein a slice is a portion of the data to be written to each disk in the RAID; and maintaining information in the RAID for slices that have been written to disk. A system for efficiently writing data to a RAID includes a buffer, a parity generating device, transfer means, and a metadata portion in the RAID. The buffer receives data from a host and accumulates data until a complete slice is accumulated. The parity generating device reads data from the buffer and generates parity based on the read data. The transfer means transfers data from the buffer and the generated parity to the disks of the RAID. The metadata portion is configured to store information for slices that have been written to disk.

Claims

1. A method for writing data to a redundant array of inexpensive disks (RAID), comprising the steps of:

writing an entire slice to the RAID at one time, wherein a slice is a portion of the data to be written to each disk in the RAID; and

maintaining information in the RAID for the slices that have been written to disk.

2. The method according to claim 1, wherein the maintained information is used to improve recovery performance in the event of a disk failure.

3. The method according to claim 2, wherein the recovery performance is improved by only recovering those slices that have previously been written to disk.

4. The method according to claim 1, wherein the maintained information is used to track which slices have been written to disk.

5. The method according to claim 1, further comprising the step of:

aggregating the maintained information for each slice into a single disk portion in the RAID.

6. The method according to claim 1, wherein the maintaining step includes maintaining information for the slices that have not been written to disk.

7. The method according to claim 6, wherein the maintained information is used to track which slices have not been written to disk.

8. A system for writing data to a redundant array of inexpensive disks (RAID), comprising:

a buffer, configured to receive data from a host and configured to accumulate data until a complete slice is accumulated, wherein a slice is a portion of the data to be written to each disk in the RAID;

a parity generating device, configured to read data from said buffer and to generate parity based on the read data;

transfer means for transferring data from said buffer and the generated parity to the disks of the RAID; and

a metadata portion in the RAID, said metadata portion configured to store information for slices that have been written to disk.

9. The system according to claim 8, wherein said transfer means includes direct memory access to transfer the data from said buffer and the generated parity to the disks of the RAID.

10. The system according to claim 8, further comprising:

a plurality of buffers for accumulating data, one buffer associated with one disk of the RAID.

11. The system according to claim 10, wherein said transfer means transfers data from each of said plurality of buffers when a complete slice has been accumulated.

12. The system according to claim 8, wherein said transfer means transfers data to disk while said parity generating device is generating the parity for the data.

13. The system according to claim 8, wherein said metadata portion is configured to store information for slices that have not been written to disk.

14. A computer-readable storage medium containing a set of instructions for a general purpose computer, the set of instructions comprising:

a writing code segment for writing an entire slice to a redundant array of inexpensive disks (RAID) at one time, wherein a slice is a portion of the data to be written to each disk in the RAID; and

a maintaining code segment for maintaining information in the RAID for the slices that have been written to disk.

15. The storage medium according to claim 14, wherein said maintaining code segment includes a recovery code segment for improving recovery performance in the event of a disk failure.

16. The storage medium according to claim 15, wherein said recovery code segment improves recovery performance by only recovering those slices that have previously been written to disk.

17. The storage medium according to claim 14, wherein said maintaining code segment includes a tracking code segment for tracking which slices have been written to disk.

18. The storage medium according to claim 14, wherein the set of instructions further comprises:

an aggregating code segment for aggregating the maintained information for each slice into a single disk portion in the RAID.

19. The storage medium according to claim 14, wherein said maintaining code segment includes a tracking code segment for tracking which slices have not been written to disk.