System and method for raid management, reallocation, and restriping

• US 8,230,193 B2
• Filed: 02/07/2011
• Issued: 07/24/2012
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: Dell International LLC (Dell Technologies Inc.)
• Original Assignee: Compellent Technologies Incorporated (Dell Technologies Inc.)
• Inventors: Klemm, Michael J., Uttormark, Michael J.
• Primary Examiner(s): Dudek, Jr., Edward
• Assistant Examiner(s): Verderamo, III, Ralph A
• Application Number:
  US13/022,074
• Publication Number:
  US 20110167219A1
• Time in Patent Office: 533 Days
• Field of Search: 711/170, 711/E12.084
• US Class Current: 711/165
• CPC Class Codes: G06F 2211/1004 Adaptive RAID, i.e. RAID system adapts to changing circumstances, e.g. RAID1 becomes RAID5 as disks fill up
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

The present disclosure relates to systems and methods for RAID Restriping. One method includes selecting an initial RAID device for migration based on at least one score, creating an alternate RAID device, moving data from the initial RAID device to the alternate RAID device, and removing the initial RAID device. The method may be performed automatically by the system or manually. The method may be performed periodically, continuously, after every RAID device migration, upon addition of disk drives, and/or before removal of disk drives, etc. One system includes a RAID subsystem and a disk manager configured to automatically calculate a score for each RAID device, select a RAID device based on the relative scores of the RAID devices, create an alternate RAID device, move data from the selected RAID device to the alternate RAID device, and remove the selected RAID device.

Claims

1. A method of data migration in a disk drive system, comprising the steps of:

determining an initial score for each of a plurality of data storage devices, the initial score relating to a respective one of the plurality of data storage devices in its present state;

determining a second score for each of the plurality of data storage devices, the second score relating to a data storage device that could be constructed from storage space in the disk drive system; and

selecting a data storage device for migration to a new data storage device based on a relative comparison of at least one of the initial score or a combination of the initial score and the second score between each of the plurality of data storage devices, the selected data storage device comprising a data storage device with the worst relative combination of the initial score and the second score.

2. The method of claim 1, further comprising moving data stored at the selected data storage device to the new data storage device and removing the selected data storage device.

3. The method of claim 2, wherein the plurality of data storage devices are RAID devices, and wherein scores are each calculated based on at least one of factors comprising the RAID level, RAID stripe size, RAID extent size, disk category, location on disk, disk enclosure, disk enclosure power supply, and communication path to the disk.

4. The method of claim 3, wherein the factors have varying weights.

5. The method of claim 2, wherein moving data stored at the selected data storage device to the new data storage device further comprises creating at least one temporary data storage device.

6. The method of claim 5, further comprising moving data stored at the selected data storage device to the at least one temporary data storage device and then from the temporary data storage device to the new data storage device.

7. The method of claim 2, wherein the selected data storage device comprises a data storage device with an initial score worse than its second score.

8. The method of claim 2, wherein the selected data storage device comprises a data storage device with the worst relative initial score.

9. The method of claim 1, wherein the initial scores and the second scores are based on RAID parameters of the respective data storage devices.

10. The method of claim 1, wherein the initial scores and the second scores are based on the location of the respective data storage devices on the disk drive system.

11. The method of claim 1, wherein the data storage device that could be constructed from storage space in the disk drive system is a data storage device that could be constructed from existing available space.

12. The method of claim 1, wherein the data storage device that could be constructed from storage space in the disk drive system is a data storage device that could be constructed from a combination of existing available disk space and at least a portion of the disk space taken up by the respective data storage device.

13. A disk drive system, comprising:

a data storage subsystem; and

a disk manager having at least one disk storage system controller configured to automatically;

calculate an initial score for each data storage device of a plurality of data storage devices of the data storage subsystem, the initial score relating to a respective one of the plurality of data storage devices in its present state, and calculate a second score for each data storage device of the plurality of data storage devices of the data storage system, the second score relating to a data storage device that could be constructed from storage space in the disk drive system; and

select at least one data storage device from the plurality of data storage devices for migration to a new data storage device based on a relative comparison of at least one of the initial score or a combination of the initial score and the second score between each of the plurality of data storage devices, the selected data storage device comprising a data storage device with the worst relative combination of the initial score and the second score.

14. The disk drive system of claim 13, wherein the controller is further configured to move at least a portion of the data stored at the selected data storage device to the new data storage device, and remove the selected data storage device.

15. The disk drive system of claim 13, further comprising a virtual volume allocated across a plurality of the data storage devices.

16. The disk drive system of claim 13, wherein at least one of the data storage devices comprises portions of a plurality of virtual volumes.

17. The disk drive system of claim 13, wherein the data storage device that could be constructed from storage space in the disk drive system is a data storage device that could be constructed from existing available space.

18. The disk drive system of claim 13, wherein the data storage device that could be constructed from storage space in the disk drive system is a data storage device that could be constructed from a combination of existing available disk space and at least a portion of the disk space taken up by the respective data storage device.

19. A method of data migration in a disk drive system, comprising the steps of:

determining an initial score for each of a plurality of data storage devices, the initial score relating to a respective one of the plurality of data storage devices in its present state;

determining a second score for each of the plurality of data storage devices, the second score relating to a data storage device that could be constructed from storage space in the disk drive system; and

selecting a data storage device for migration to a new data storage device based on a relative comparison of at least one of the initial score or a combination of the initial score and the second score between each of the plurality of data storage devices, the selected data storage device comprising a data storage device with the largest difference between its respective initial and second scores.

20. A disk drive system, comprising:

a data storage subsystem; and

a disk manager having at least one disk storage system controller configured to automatically;

calculate an initial score for each data storage device of a plurality of data storage devices of the data storage subsystem, the initial score relating to a respective one of the plurality of data storage devices in its present state, and calculate a second score for each data storage device of the plurality of data storage devices of the data storage system, the second score relating to a data storage device that could be constructed from storage space in the disk drive system; and

select at least one data storage device from the plurality of data storage devices for migration to a new data storage device based on a relative comparison of at least one of the initial score or a combination of the initial score and the second score between each of the plurality of data storage devices, the selected data storage device comprising a data storage device with the largest difference between its respective initial and second scores.