Systems and methods for managing stalled storage devices

• US 7,971,021 B2
• Filed: 12/16/2010
• Issued: 06/28/2011
• Est. Priority Date: 03/27/2008
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Passey, Aaron J., Akidau, Tyler A., Daud, Asif, Maykov, Ilya
• Primary Examiner(s): BATAILLE, PIERRE MICHE
• Application Number:
  US12/970,795
• Publication Number:
  US 20110087928A1
• Time in Patent Office: 194 Days
• Field of Search: 711/167, 711/147, 711/165, 711/119, 711/112, 711/E12.002, 726/2, 718/100, 714/5, 714/42
• US Class Current: 711/167
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/0715 in a system implementing multitasking multitasking per se G06F9/46
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/0745 in an input/output transactions management context input/output processing in general G06F13/00
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence

Abstract

Embodiments relate to systems and methods for managing stalled storage devices of a storage system. In one embodiment, a method for managing access to storage devices includes determining that a first storage device, which stores a first resource, is stalled and transitioning the first storage device to a stalled state. The method also includes receiving an access request for at least a portion of the first resource while the first storage device is in the stalled state and attempting to provide access to a representation of the portion of the first resource from at least a second storage device that is not in a stalled state. In another embodiment, a method of managing access requests by a thread for a resource stored on a storage device includes initializing a thread access level for an access request by a thread for the resource. The method also includes determining whether the storage device, which has a device access level, is accessible based at least in part on the thread access level and the device access level and selecting a thread operation based at least in part on the determination of whether the storage device is accessible. The thread operation may be selected from attempting the thread access request if the device is accessible and determining whether to restart the thread access request if the device is not accessible.

Claims

1. A method of managing access requests for resources stored on a storage system, the method comprising:

under control of a storage system comprising a plurality of storage devices, each storage device comprising a device access level, the device access level comprising a normal access level and a stalled access level, the normal access level indicating that response to access requests to the storage device is normal and the stalled access level indicating that response to access requests to the storage device is slow,

directing a first access request by a thread for a resource stored on the storage system to one or more storage devices comprising normal access levels near the time of the first access request; and

if the first access request by the thread fails,

directing a second access request by the thread for the resource to one or more storage devices comprising normal access levels near the time of the second access request and one or more storage devices comprising stalled access levels near the time of the second access request.

2. The method of claim 1, wherein at least one of the one or more storage devices comprising normal access levels near the time of the second access request is the same as at least one of the one or more storage devices comprising normal access levels near the time of the first access request.

3. The method of claim 1, wherein the device access level further comprises a soft-failed access level that indicates that an error not related to resource access requests to the storage device has occurred on the storage device, the method further comprising:

if the second access request by the thread fails,

directing a third access request by the thread for the resource to one or more storage devices comprising normal access levels near the time of the third access request, one or more storage devices comprising stalled access levels near the time of the third access request, and one or more storage devices comprising soft-failed access levels near the time of the third access request.

4. The method of claim 3, wherein if the third access request by the thread fails, the method further comprises returning an error to the thread.

5. The method of claim 1, wherein a stalled access level for a storage device indicates that response by the storage device to access requests is longer than a first time period.

6. The method of claim 1, further comprising performing a group change operation such that each of the storage devices in the storage system has information related to the current device access level of each of the other storage devices in the storage system.

7. The method of claim 6, wherein the time of the first access request is before the performance of the group change operation, and the time of the second access request is after performance of the group change operation.

8. The method of claim 1, wherein directing the first access request by the thread comprises:

initializing a thread access level for the first access request by the thread;

determining which of the plurality of storage devices to direct the first access request to based at least in part on the thread access level and the device access levels of the plurality of storage devices;

if at least one storage device is determined to be accessible, attempting the first access request from the at least one accessible storage device; and

if no storage devices are determined to be accessible, determining whether to attempt the second access request.

9. The method of claim 1, wherein the storage system comprises a distributed file system.

10. A system of managing access requests for resources stored on a plurality of storage devices, the system comprising:

a plurality of storage devices configured to store a resource, each storage device comprising a device access level, the device access level comprising a normal access level and a stalled access level, the normal access level indicating that response to access requests to the storage device is normal and the stalled access level indicating that response to access requests to the storage device is slow,

a processor in communication with at least some of the plurality of storage devices, the processor configured to;

direct a first access request by a thread for the resource to one or more storage devices comprising normal access levels near the time of the first access request; and

if the first access request by the thread fails,

direct a second access request by the thread for the resource to one or more storage devices comprising normal access levels near the time of the second access request and one or more storage devices comprising stalled access levels near the time of the second access request.

11. The system of claim 10, wherein at least one of the one or more storage devices comprising normal access levels near the time of the second access request is the same as at least one of the one or more storage devices comprising normal access levels near the time of the first access request.

12. The system of claim 10, wherein the device access level further comprises a soft-failed access level that indicates an error that is not related to resource access requests to the storage device has occurred on the storage device, the processor further configured to:

if the second access request by the thread fails,

direct a third access request by the thread for the resource to one or more storage devices comprising normal access levels near the time of the third access request, one or more storage devices comprising stalled access levels near the time of the third access request, and one or more storage devices comprising soft-failed access levels near the time of the third access request.

13. The system of claim 12, wherein if the third access request by the thread fails, the processor is configured to return an error to the thread.

14. The system of claim 10, wherein a stalled access level for a storage device indicates that response by the storage device to access requests is longer than a first time period.

15. The system of claim 10, wherein the processor is further configured to perform a group change operation such that each of the plurality of storage devices has information related to the current device access level of each of the other storage devices.

16. The system of claim 15, wherein the time of the first access request is before the processor performs the group change operation, and the time of the second access request is after the processor performs of the group change operation.

17. The system of claim 10, wherein to direct the first access request by the thread, the processor is configured to:

initialize a thread access level for the first access request by the thread;

determine which of the plurality of storage devices to direct the first access request to based at least in part on the thread access level and the device access levels of the plurality of storage devices;

if at least one storage device is determined to be accessible, attempt the first access request from the at least one accessible storage device; and

if no storage devices are determined to be accessible, determine whether to attempt the second access request.

18. The system of claim 10, wherein the plurality of storage devices comprises a portion of a distributed file system.

19. A non-transitory computer-readable medium having stored thereon executable instructions that, when executed by a processor, cause the processor to perform a method of managing access requests for resources stored on a storage system, the storage system comprising a plurality of storage devices, each storage device comprising a device access level, the device access level comprising a normal access level and a stalled access level, the normal access level indicating that response to access requests to the storage device is normal and the stalled access level indicating that response to access requests to the storage device is slow, the method comprising:

directing a first access request by a thread for a resource stored on the storage system to one or more storage devices comprising normal access levels near the time of the first access request; and

if the first access request by the thread fails,

directing a second access request by the thread for the resource to one or more storage devices comprising normal access levels near the time of the second access request and one or more storage devices comprising stalled access levels near the time of the second access request.