Systems and methods for managing unavailable storage devices

• US 8,286,029 B2
• Filed: 12/21/2006
• Issued: 10/09/2012
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Anderson, Robert J., Fachan, Neal T., Godman, Peter J., Husted, Justin M., Passey, Aaron J., Richards, David W., Schack, Darren P.
• Primary Examiner(s): SCHELL, JOSEPH O
• Application Number:
  US11/643,725
• Publication Number:
  US 20080151724A1
• Time in Patent Office: 2,119 Days
• Field of Search: 714 1- 7, 714/15, 714/6.3, 714/6.32, 714/6.1, 714/6.2, 714/6.22, 714/6.24
• US Class Current: 714/6.32
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G11B 33/127 Mounting arrangements of constructional parts onto a chassis

Abstract

In some embodiments, storage devices, such as a storage drive or a storage node, in an array of storage devices may be reintroduced into the array of storage devices after a period of temporary unavailability without fully rebuilding the entire previously unavailable storage device.

Claims

1. A storage system for managing unavailable storage devices comprising:

a plurality of storage devices comprising at least a first storage device and a second storage device;

one or more computer processors, each of the one or more computer processors in electronic communication with one or more of the plurality of storages devices; and

at least one executable software module executed by the one or more computer processors, wherein the executable software module is configured to reconstruct data on an unavailable device on a read request, wherein the read request does not result in the executable software module copying the reconstructed data to an alternate available device, and wherein the executable software module is configured to;

store a set of data on the plurality of storage devices, wherein the set of data comprises a plurality of blocks, and wherein storing the set of data comprises storing at least a first block and a second block on the first storage device;

determine that the first storage device is unavailable;

receive a read request corresponding to the first block on the first storage device;

in response to the read request, reconstruct the first block using one or more other blocks in the plurality of blocks, wherein the read request does not trigger modifying an association between the first block and the first storage device in metadata based on a future availability of the first storage device after a period of temporary unavailability;

return the reconstructed data block;

receive a write request comprising a request to write an updated block corresponding to the second block;

in response to the write request,

store the updated block on a second storage device in the plurality of storage devices, the second storage device different from the first storage device, and

modify an association between the second block and the first storage device in metadata to reflect an association between the second block and the second storage device,

determine that the first storage device is available after a period of unavailability; and

in response to determining that the first storage device is available, free the second block on the first storage device.

2. The storage system of claim 1, wherein the storage system is a file system.

3. The storage system of claim 2, wherein the file system is a distributed file system.

4. The storage system of claim 1, wherein the at least one executable software module is further configured to, in response to the write request, store the updated block in a journal.

5. The storage system of claim 4, wherein the at least one executable software module is further configured to flush the updated block from the journal to the first storage device when the first storage device is available.

6. The storage system of claim 1, wherein the set of data comprises a plurality of blocks of data and at least one of the first block and the second block comprises a parity block.

7. The storage system of claim 1, wherein the set of data comprises mirrored data, and the first block comprises a mirror of a third block in the set of data.

8. The storage system of claim 1, wherein storing the set of data on the plurality of storage devices comprises storing the set of data on a subset of storage devices of the plurality of storage devices, and wherein the subset of storage devices comprises less than all the storage devices in the plurality of storage devices.

9. The storage system of claim 8, wherein storing the set of data on the subset of storage devices of the plurality of storage devices comprises storing at least one block of data on each storage device in the subset of storage devices.

10. The storage system of claim 9, wherein the second storage device in the plurality of storage devices is a member of the subset of storage devices.

11. The storage system of claim 9, wherein the second storage device in the plurality of storage devices is not a member of the subset of storage devices.

12. The storage system of claim 1, wherein the at least one executable software module is further configured to store the set of data on the plurality of storage devices based on a parity protection plan.

13. The storage system of claim 12, wherein storing the updated block on the second storage device in the plurality of storage devices satisfies the parity protection plan.

14. The storage system of claim 12, wherein storing the updated block on the second storage device in the plurality of storage devices does not satisfy the parity protection plan.

15. The storage system of claim 1, wherein at least one executable software module is further configured to store a second set of data on the plurality of storage devices, wherein the second set of data comprises a second plurality of blocks, and wherein storing the second set of data comprises storing at least a third block on the first storage device and a fourth block on the second storage device.

16. The storage system of claim 1, wherein the set of data comprises a second set of metadata.

17. The storage system of claim 16, wherein the second set of metadata comprises at least a mirrored copy of the first set of metadata.