Systems and methods for managing unavailable storage devices

• US 20080151724A1
• Filed: 12/21/2006
• Published: 06/26/2008
• 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: Husted, Justin M., Schack, Darren P., Passey, Aaron J., Godman, Peter J., Anderson, Robert J., Fachan, Neal T., Richards, David W.
• Granted Patent: US 8,286,029 B2
• Time in Patent Office: Days
• US Class Current: 369/53.42
• 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 method for managing unavailable storage devices comprising:

detecting that a troubled storage device is unavailable, wherein a data set is stored on the troubled storage device;

responding to a read or write request for data at least a portion of the data set while the troubled storage device is unavailable; and

detecting that the troubled storage device is available and providing access to the data set stored on the troubled storage device without full reconstruction of the troubled storage device.

2. The method of claim 1, wherein the troubled storage device and the at least one operational storage device comprise at least a portion of a file system.

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

4. The method of claim 1, wherein the troubled storage device is unavailable due to at least one of a timeout, an accidental disconnection, a faulty cable, a vibration, an irregularity in the power supply, an abnormal temperature, an excessive duty cycle, and aberrant or unreliable device operation.

5. The method of claim 1, wherein access to the troubled storage device is provided automatically when the troubled storage device becomes available.

6. The method of claim 1, wherein storage of the representation of at least a portion of the data set is distributed over a plurality of the at least one operational storage devices.

7. The method of claim 1, wherein the troubled storage device is at least one of a hard drive, a magnetic storage medium, an optical storage medium, a volatile or non-volatile memory, a plurality of hard drives, a plurality of storage mediums, and a partitioned portion of a hard drive.

8. The method of claim 1, wherein the at least one operational storage device is at least one of, a hard drive, a magnetic storage medium, an optical storage medium, a volatile or non-volatile memory, a plurality of hard drives, a plurality of storage mediums, and a partitioned portion of a hard drive.

9. The method of claim 3, wherein the troubled storage device and the at least one operational storage device are configured to communicate with one another, and the troubled storage device indicates whether it is available or unavailable.

10. The method of claim 1, wherein the troubled storage device permits the at least one operational storage device to determine whether it is available or unavailable.

11. The method of claim 1, further comprising:

storing a record of transactions that relate to the troubled storage device in a journal; and

storing data to be written to the troubled storage device in the journal when the troubled storage device is unavailable.

12. The method of claim 11, wherein the journal is comprised of at least one of an NVRAM, a Flash ROM, an EEPROM, a magnetic tape, and a disk.

13. The method of claim 1, further comprising:

storing a copy of the data set on one or more of the at least one plurality of operational storage devices.

14. The method of claim 13, further comprising:

modifying at least one structure that references the data set to reference the copy of the data set.

15. The method of claim 13, further comprising:

reallocating space in the troubled storage device after the troubled storage device returns to service.

16. The method of claim 14, further comprising:

deleting one or more data structures in the troubled storage device after the troubled storage device returns to service.

17. The method of claim 1, further comprising:

scanning the troubled storage device;

identifying additional data on the troubled storage device when the troubled storage device is unavailable; and

moving the additional data to one or more of the at least one operational storage devices.

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

a first storage device configured to;

store a data set; and

respond to a read or write request for at least a portion of the data set after the first storage device returns from an unavailable state without full reconstruction of the first storage device; and

at least one operational storage device configured to;

store a representation of at least a portion of the data set; and

provide access to the representation of at least a portion of the data set if the first storage device is unavailable.

19. The storage system of claim 18, wherein the storage system is a file system.

20. The storage system of claim 19, wherein the file system is a distributed file system.

21. The storage system of claim 18, wherein the first storage device is unavailable due to at least one of a timeout, an accidental disconnection, a faulty cable, a vibration, an irregularity in the power supply, an abnormal temperature, an excessive duty cycle, and aberrant or unreliable device operation.

22. The storage system of claim 18, wherein the first storage device is automatically reconnected to the storage system when it becomes available.

23. The storage system of claim 18, wherein storage of the representation of at least a portion of the data set is distributed over a plurality of the at least one operational storage devices.

24. The storage system of claim 18, wherein the first storage device is at least one of a hard drive, a magnetic storage medium, an optical storage medium, a volatile or non-volatile memory, a plurality of hard drives, a plurality of storage mediums, and a partitioned portion of a hard drive.

25. The storage system of claim 18, wherein the at least one operational storage device is at least one of a hard drive, a magnetic storage medium, a plurality of hard drives, a plurality of magnetic storage media, and a partitioned portion of a hard drive.

26. The storage system of claim 20, wherein the first storage device and the at least one operational storage device are configured to communicate with one another, and the first storage device indicates whether it is available or unavailable.

27. The storage system of claim 18, wherein the first storage device permits the at least one operational storage device to determine whether it is available or unavailable.

28. The storage system of claim 18, further comprising:

one or more processors configured to;

store a record of transactions that relate to the first storage device in a journal; and

store data to be written to the first storage device in the journal when the first storage device is unavailable.

29. The storage system of claim 28, wherein the journal is comprised of at least one of an NVRAM, a Flash ROM, an EEPROM, a magnetic tape, and a disk.

30. The storage system of claim 18, further comprising:

a processor configured to store a copy of the data set on one or more of the at least one plurality of operational storage devices.

31. The storage system of claim 30, wherein the processor modifies at least one structure that references the data set to reference the copy of the data set.

32. The storage system of claim 30, wherein the processor is further configured to reallocate space in the first storage device after the first storage device returns to service.

33. The storage system of claim 31, wherein the processor is further configured to deleting one or more data structures in the first storage device after the first storage device returns to service.

34. The storage system of claim 18, further comprising a processor configured to:

scan the first storage device;

identify additional data stored on the first storage device when the first storage device is unavailable; and

move the additional data to one or more of the at least one operational storage devices.

35. A storage system for managing storage devices comprising:

a plurality of storage devices configured to store data distributed among at least two of the plurality of storage devices;

wherein if one or more of the plurality of storage devices becomes unavailable and then becomes available again, the data is available after the one or more of the plurality of storage devices becomes available again.

36. The storage system of claim 35, where the data is available without fully reconstructing the one or more plurality of storage devices that becomes available again.