Use of activity bins to increase the performance of disk arrays

• US 6,567,892 B1
• Filed: 05/23/2001
• Issued: 05/20/2003
• Est. Priority Date: 05/23/2001
• Status: Expired due to Fees

• Current Assignee: Summit Data Systems LLC (Acacia Research Corporation)
• Original Assignee: 3Ware Inc. (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Therene, Christophe, Horst, Robert W.
• Primary Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US09/863,490
• Time in Patent Office: 727 Days
• Field of Search: 711/114, 711/156, 711/161, 711/162, 711/111
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1009 Cache, i.e. caches used in RAID system with parity

Abstract

A disk array controller reliably improves performance in RAID configurations without the need for a battery backup. Write completion interrupts are queued until a write cache flush has been performed and are then sent to a host system. States of ranges of disk addresses (activity bins) are stored in nonvolatile storage elements associated with the ranges. The states allow rebuild times to be reduced after power failures and drive failures. A range is in a Changing state if at least one of the addresses is the target of a write operation that has been initiated but not completed. The range is in a Stable state if no addresses are the target of an uncompleted write operation. Two additional states are used to identify ranges of disk addresses that have been zeroed or never been written to. The additional states allow substantial reductions in RAID volume creation times.

Claims

1. A method of operating a RAID volume having an addressable storage space, the method comprising:

(a) receiving a write operation directed to a target address range;

(b) determining, based at least upon a value stored in a nonvolatile memory element separate from the target address range, that at least a portion of the target address range may not have been previously written to comply with a RAID standard; and

(c) in response to (b), processing at least the target address range to conform to the RAID standard,

whereby processing of write operations is enabled before substantially all of the addressable storage space has been configured to be compliant with the RAID standard.

2. The method of claim 1, wherein (c) comprises zeroing an address range of which the target address range is a subset.

3. The method of claim 1, wherein (c) comprises rebuilding an address range of which the target address range is a subset.

4. The method of claim 1, further comprising writing write data of the write operation to disk media of the RAID volume in conformance with the RAID standard.

5. The method of claim 1, wherein (b) comprises determining that at least a portion of the target address range has not been previously written to comply with a RAID standard.

6. The method of claim 1, wherein (b) comprises determining that at least a portion of the disk media corresponding to the target address range has not been previously written to since the RAID volume was initialized.

7. A method of operating a RAID volume having an addressable storage space, the method comprising:

(a) receiving a write operation directed to an address range;

(b) in response to (a), zeroing at least the address range to which the write operation is directed;

(c) subsequent to (b), performing the write operation,

whereby processing of write operations is enabled before substantially all of the addressable storage space has been configured to be compliant with a RAID standard.

8. The method of claim 7, wherein the address range has not been the target of a write operation since the RAID volume was created.

9. The method of claim 7, further comprising initiating a zeroing process to zero substantially the entire RAID volume, wherein (c) is performed before the zeroing process has completed.

10. A method of operating a RAID volume, the method comprising:

initiating a zeroing process to zero substantially the entire RAID volume;

receiving a write operation from a host system, wherein the write operation is directed to a logical address of the RAID volume; and

writing write data of the write operation to disk media of the RAID volume before the zeroing process has been completed,

whereby processing of write operations is enabled before substantially all of the addressable storage space has been configured to be compliant with a RAID standard.

11. The method of claim 10, wherein the step of writing the write data comprises initially accessing activity bin state information stored separately from the RAID volume to determine whether an address range to which the write operation corresponds has been zeroed.

12. The method of claim 10, further comprising, prior to writing the write data to the disk media, zeroing an address range to which the write operation corresponds if the address range has not already been zeroed by said zeroing process.

13. A method of operating a RAID volume, the method comprising:

for each of a plurality of ranges of multiple addresses representing substantially the entire addressable storage space of the RAID volume, maintaining an associated memory element in nonvolatile storage;

for each of the ranges of addresses, maintaining, in the associated memory element, state information reflective of whether data stored in the respective range of addresses conforms to a RAID standard; and

using the state information stored in the memory elements to do at least one of the following;

(a) identify ranges of addresses that need not be rebuilt during a rebuild operation, so that rebuild times may be reduced, (b) defer zeroing of address ranges so that write operations may commence following RAID volume creation before zeroing of the RAID volume is complete.

14. The method of claim 13, wherein the state information indicates, for at least some of the ranges of addresses, whether such ranges of addresses have been written to since creation of the RAID volume.

15. The method of claim 13, wherein the state information indicates, for at least some of the ranges of addresses, whether such ranges of addresses have been zeroed since creation of the RAID volume.

16. The method of claim 13, wherein the state information indicates, for at least some of the ranges of addresses, whether such ranges of addresses are in a stable state.

17. The method of claim 13, wherein the nonvolatile storage is implemented within solid state storage of a disk array controller.

18. The method of claim 13, wherein the method comprises using the state information to identify ranges of addresses that need not be rebuilt during a rebuild operation, so that rebuild times may be reduced.

19. The method of claim 13, wherein the method comprises using the state information to defer zeroing of address ranges so that write operations may commence following RAID volume creation before zeroing of the RAID volume is complete.

20. A method of operating a RAID volume, the method comprising:

for each of a plurality of ranges of multiple addresses representing substantially the entire addressable storage space of the RAID volume, maintaining an associated memory element in nonvolatile storage;

for each of the ranges of addresses, setting the associated memory element to indicate at least that the range has not been written to since the RAID volume was created;

identifying a write command directed to at least one of the ranges of addresses; and

for at least one range of addresses to which the write command is directed;

zeroing the at least one range of addresses, and

setting each of the memory elements associated with the at least one range of addresses to indicate at least that the range of addresses associated with the memory element has been zeroed.

21. The method of claim 20, further comprising for the at least one range of addresses to which the write command is directed:

writing write data associated with the write command to disk media of the RAID volume, and

setting each of the memory elements associated with the at least one range of addresses to indicate at least that data has been written to disk media associated with the range of addresses associated with the memory element.

22. The method of claim 21, further comprising, prior to writing the write data, setting each of the memory elements associated with the at least one range of addresses to indicate at least that a write operation directed to the range of addresses associated with the memory element has been initiated.

23. A RAID array comprising:

a plurality of disk drives;

a binmap comprising a plurality of storage elements maintained in nonvolatile memory, wherein each storage element is associated with an activity bin; and

at least one processor configured to;

operate the disk drives in a RAID configuration,

map disk addresses to activity bins, and

store disk activity data in the binmap;

wherein the at least one processor is further configured to skip the rebuilding of at least one range of addresses associated with a target activity bin based at least upon activity data stored in association with the target activity bin.

24. The RAID array of claim 23, wherein the disk activity data indicates which of the activity bins may be treated as conforming to a RAID standard.

25. The RAID array of claim 23, wherein the disk activity data indicates, for at least some of the activity bins, whether such activity bins are in a stable state.

26. The RAID array of claim 23, wherein the disk activity data indicates, for at least some of the activity bins, whether such activity bins have been zeroed since creation of a RAID volume.

27. The RAID array of claim 23, wherein the disk activity data indicates, for at least some of the activity bins, whether such activity bins have been written to since creation of a RAID volume.

28. A RAID array comprising:

a plurality of disk drives;

a binmap comprising a plurality of storage elements maintained in nonvolatile memory, wherein each storage element is associated with an activity bin; and

at least one processor configured to;

operate the disk drives in a RAID configuration,

map disk addresses to activity bins, and

store disk activity data in the binmap;

wherein the at least one processor is further configured to zero a range of addresses associated with a target activity bin at least in response to a receipt of a write operation directed to the target activity bin.

29. The RAID array of claim 28, wherein the disk activity data indicates which of the activity bins may be treated as conforming to a RAID standard.

30. The RAID array of claim 28, wherein the disk activity data indicates, for at least some of the activity bins, whether such activity bins have been zeroed since creation of a RAID volume.

31. The RAID array of claim 28, wherein the disk activity data indicates, for at least some of the activity bins, whether such activity bins have been written to since creation of a RAID volume.

32. A method of operating a disk array, comprising:

executing a background task to zero address ranges of the disk array, such that the background task executes concurrently with the processing of write operations to the disk array;

maintaining state information separately from the address ranges of the disk array, said state information indicating which of the address ranges have been zeroed; and

in response to receipt of a write operation to a target address range, using the state information to determine whether the target address range has been zeroed.

33. The method of claim 32, further comprising zeroing the target address range prior to executing the write operation if the state information indicates that the target address range has not yet been zeroed.

34. The method of claim 32, wherein the disk array is configured as a RAID array.