Sparse raid rebuild based on storage extent allocation
First Claim
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1. A method of repairing a RAID (Redundant Array of Independent Disks) group in a data storage system following a failure of a disk drive in the RAID group, the method comprising:
- providing a spare disk drive to replace the disk drive in the RAID group that failed;
accessing metadata in the data storage system, the metadata indicating an allocation status of multiple storage extents formed from the RAID group, the storage extents formed from the RAID group including a first set of storage extents that the metadata indicates is not allocated and a second set of storage extents that the metadata indicates is allocated;
for each of the first set of storage extents, writing predetermined data to the spare disk drive at regions that will support that storage extent; and
for each of the second set of storage extents, (i) reading portions of data from regions that support that storage extent on a set of other disk drives of the RAID group, (ii) providing repair data for that storage extent based on the portions of data read for that storage extent, and (iii) writing the repair data for that storage extent to the spare disk drive,the method thereby avoiding any need to read portions of data from other disk drives for storage extents that are not allocated.
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Abstract
A technique for repairing a RAID (Redundant Array of Independent Disks) group in a data storage system following a failure of a disk drive in the RAID group includes identifying regions of the failed disk drive that supported unallocated storage extents and writing predetermined data to corresponding regions of the spare disk drive. Any reading of other disk drives in the RAID group may thus be limited only to those regions of the failed disk drive that supported allocated storage extents.
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Citations
21 Claims
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1. A method of repairing a RAID (Redundant Array of Independent Disks) group in a data storage system following a failure of a disk drive in the RAID group, the method comprising:
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providing a spare disk drive to replace the disk drive in the RAID group that failed; accessing metadata in the data storage system, the metadata indicating an allocation status of multiple storage extents formed from the RAID group, the storage extents formed from the RAID group including a first set of storage extents that the metadata indicates is not allocated and a second set of storage extents that the metadata indicates is allocated; for each of the first set of storage extents, writing predetermined data to the spare disk drive at regions that will support that storage extent; and for each of the second set of storage extents, (i) reading portions of data from regions that support that storage extent on a set of other disk drives of the RAID group, (ii) providing repair data for that storage extent based on the portions of data read for that storage extent, and (iii) writing the repair data for that storage extent to the spare disk drive, the method thereby avoiding any need to read portions of data from other disk drives for storage extents that are not allocated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 21)
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10. A data storage system comprising control circuitry that includes a set of processing units coupled to memory, the control circuitry constructed and arranged to:
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provide a spare disk drive to replace the disk drive in the RAID group that failed; access metadata in the data storage system, the metadata indicating an allocation status of multiple storage extents formed from the RAID group, the storage extents formed from the RAID group including a first set of storage extents that the metadata indicates is not allocated and a second set of storage extents that the metadata indicates is allocated; and for each of the first set of storage extents, write predetermined data to the spare disk drive at regions that will support that storage extent; for each of the second set of storage extents, (i) read portions of data from regions that support that storage extent on a set of other disk drives of the RAID group, (ii) provide repair data for that storage extent based on the portions of data read for that storage extent, and (iii) write the repair data for that storage extent to the spare disk drive. - View Dependent Claims (11)
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12. A computer program product including a set of non-transitory, computer-readable media having instructions which, when executed by control circuitry of a data storage system, cause the control circuitry to perform a method for repairing a RAID (Redundant Array of Independent Disks) group in a data storage system following a failure of a disk drive in the RAID group, the method comprising:
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providing a spare disk drive to replace the disk drive in the RAID group that failed; accessing metadata in the data storage system, the metadata indicating an allocation status of multiple storage extents formed from the RAID group, the storage extents formed from the RAID group including a first set of storage extents that the metadata indicates is not allocated and a second set of storage extents that the metadata indicates is allocated; for each of the first set of storage extents, writing predetermined data to the spare disk drive at regions that will support that storage extent; and for each of the second set of storage extents, (i) reading portions of data from regions that support that storage extent on a set of other disk drives of the RAID group, (ii) providing repair data for that storage extent based on the portions of data read for that storage extent, and (iii) writing the repair data for that storage extent to the spare disk drive, the method thereby avoiding any need to read portions of data from other disk drives for storage extents that are not allocated. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification