Granted Patent B2

US 7,330,931 · App. 11/322,787 · Granted Feb 12, 2008

Abstract

Claims (80)

1. A method for preparing data units for access in a data storage system, the data storage system comprising a plurality of storage devices having data units, wherein not all of the storage devices are powered on at the same time, the method comprising:

preparing auxiliary data for a data unit on a data unit storage device that will be powered down during an access request of the data unit; and

storing the auxiliary data on one or more of the storage devices so that the auxiliary data is always available on a powered-on storage device when the data unit is a subject of an access request while the data unit storage device is powered down, wherein after receiving the access request, the powered-on storage device is not powered-on from a powered down state to respond to the access request.

2. The method of claim 1 , wherein the auxiliary data is stored on all of the storage devices.

3. The method of claim 1 , further comprising:

using an auxiliary data area on a storage device to store the auxiliary data; and

updating the auxiliary data.

4. The method of claim 3 , further comprising:

using a change log and a generation identification number to update the auxiliary data.

5. The method of claim 4 , wherein the generation identification number is incremented each time the auxiliary data is updated.

6. The method of claim 4 , wherein the auxiliary data is updated on the auxiliary data area when the generation identity number is not latest.

7. The method of claim 4 , wherein the change log includes updates corresponding to each increment of the generation identification number.

8. The method of claim 3 , wherein the auxiliary data is updated from one set of storage devices to a next set of storage devices when the next set of storage devices is being powered on upon the access request.

9. The method of claim 3 , wherein updating the auxiliary data comprises:

modifying the auxiliary data on all of powered-on storage devices of the data storage system when the access request is a write operation.

10. The method of claim 1 , wherein the auxiliary data is read from one of powered-on storage devices of the data storage system when the access request is a read operation.

11. The method of claim 1 , wherein the access request is received from a host.

12. The method of claim 1 , wherein preparing the auxiliary data for the data unit comprises:

configuring the data storage system during a boot cycle of the data storage system; and

synchronizing the auxiliary data in all data units of the data storage system.

13. The method of claim 12 , wherein configuring the data storage system comprises:

assigning an auxiliary data area on each storage device of the data storage system to a set of logical blocks of one or more data units of the data storage system; and

collecting the auxiliary data from the auxiliary data area to the set of logical blocks of the one or more data units.

14. The method of claim 12 , further comprising:

reconfiguring auxiliary data areas on all of the storage devices.

15. The method of claim 14 , wherein reconfiguring the auxiliary data areas comprises:

unpinning auxiliary data from the auxiliary data areas that are no longer in the configuration;

assigning new auxiliary data areas to the set of logical blocks of the one or more data units; and

collecting data from the set of logical blocks of the one or more data units to the new auxiliary data areas.

16. The method of claim 15 , wherein reconfiguring the auxiliary data areas further comprises:

modifying the set of logical blocks by using a vendor unique command that is received through one of an out-of-band and an in-band interface.

17. The method of claim 16 , further comprising:

synchronizing data in the auxiliary data areas.

18. The method of claim 1 , further comprising:

maintaining the auxiliary data on a set of storage devices of the plurality of storage devices in a background mode when a storage management unit of the data storage system is idle for a predetermined time.

19. The method of claim 18 , wherein maintaining the auxiliary data comprises:

powering on the set of storage devices in the background mode.

20. The method of claim 19 , wherein powering on the set of storage devices further comprises:

periodically swapping powered-on storage devices in the set of storage device with storage devices that are powered-off.

21. The method of claim 20 , wherein a period for periodically swapping the storage devices and the storage devices to be swapped are provided by a Self-Monitoring, Analysis and Reporting Technology (SMART) data, wherein the SMART data keeps an account of time for which each storage device in the set of storage devices is powered-on.

22. The method of claim 20 , the set of storage devices includes storage devices with least powered-on times.

23. A data storage system comprising:

a plurality of storage devices having data units, wherein not all of the storage devices are powered on at the same time;

a storage management unit capable of:

preparing auxiliary data for a data unit on a data unit storage device that will be powered down during an access request of the data unit; and

storing the auxiliary data on one or more of the storage devices in the plurality of storage devices so that the auxiliary data is always available on a powered-on storage device when the data unit is the subject of an access request while the data unit storage device is powered down, wherein after receiving the access request, the powered-on storage device is not powered-on from a powered down state to respond to the access request.

24. The data storage system of claim 23 , further comprising a controller coupled to each storage device of the plurality of storage devices, wherein the controller comprises:

a counter for incrementing a generation identification number, wherein the generation identification number is incremented each time the auxiliary data area is updated; and

a change log for storing updates corresponding to each increment of the generation identification number.

25. The data storage system of claim 24 , wherein at least one storage device of the plurality of the storage devices comprising a latest update of the auxiliary data is always powered-on.

26. The data storage system of claim 23 , further comprising a reconfiguration manager for reconfiguring auxiliary data areas on all of the storage devices.

27. The data storage system of claim 23 , further comprising an auxiliary data area management application program interface for determining logical blocks to be managed in the auxiliary data areas.

28. The data storage system of claim 23 , further comprising an auxiliary data area manager for maintaining the auxiliary data on the plurality of storage devices in a background mode when the storage management unit is idle for a predetermined time.

29. The data storage system of claim 23 , wherein the auxiliary data area is a low Mean Time to First Byte (MTFB) area in each storage device of the plurality of storage devices.

30. The data storage system of claim 29 , wherein the low MTFB area maps to a set of logical blocks, wherein the set of logical blocks is set during configuration of the data storage system.

31. An apparatus comprising:

a processor for executing instructions; and

a machine-readable medium including:

one or more instructions for preparing auxiliary data for a data unit on a data unit drive that will be powered-off during an access request of the data unit; and

one or more instructions for storing the auxiliary data on one or more storage devices so that the auxiliary data is always available on a powered-on device when the data unit is the subject of an access request while the data unit drive is powered down, wherein after receiving the access request, the powered-on storage device is not powered-on from a powered down state to respond to the access request.

32. A machine-readable medium including instructions executable by a processor for preparing data units for access in a data storage system, the data storage system comprising a plurality of storage devices having data units, wherein not all of the storage devices are powered-on at the same time, the machine readable medium comprising:

one or more instructions for preparing auxiliary data for a data unit on a data unit drive that will be powered-off during an access request of the data unit; and

one or more instructions for storing the auxiliary data on one or more of the storage devices so that the auxiliary data is always accessible and available on a powered-on device when the data unit is the subject of an access request while the data unit drive is powered down, wherein after receiving the access request, the powered-on storage device is not powered-on from a powered down state to respond to the access request.

33. A method for preparing data units for access in a data storage system, the data storage system comprising a plurality of storage devices having data units, wherein not all of the storage devices are powered on at the same time, the method comprising:

storing a data unit on a first storage device;

storing auxiliary data for the data unit on a second storage device that is in a powered-on state;

receiving an access request, wherein the first storage device is in a powered down state when the access request is received; and

responding to the access request using the auxiliary data that is stored on the second storage device that is powered-on, the second storage device not being powered on from a powered down state to service the access request.

34. The method of claim 33 , further comprising:

determining if the access request is for the auxiliary data;

responding to the request using the auxiliary data.

35. The method of claim 33 , further comprising:

determining that the second storage device will be powered down; and

moving the auxiliary data to a third storage device that is powered on such that the auxiliary data is available on a powered on storage device.

36. The method of claim 33 , wherein the auxiliary data is ensured to be on a powered on storage drive before the access request is made.

37. The method of claim 33 , further comprising:

determining if the access request is for the data unit; and

powering on the first storage device if the access request is for the data unit; and

servicing the request using the data unit on the first storage device.

38. The method of claim 33 , wherein the auxiliary data is stored on one or more additional storage devices other than the second storage device.

Assignments (8)