Method for reducing rebuild time on a RAID device
AssigneeLSI Corporation
InventorDonald Humlicek
Life of this patent
Estimating the term…
Abstract
The present invention provides a method for reducing rebuild time on a Redundant Array of Independent Disks (RAID) device. A first stripe of the RAID device is selected. Write-back caching on a drive being built is enabled. Data and/or parity may be read from at least one other drive. The at least one other drive and the drive being built belong to a same stripe of the RAID device. When a RAID level of the RAID device is 5, the at least one of data or parity is XORed (exclusive ORed) to obtain a result. When the RAID level of the RAID device is 1, the at least one of data or parity is data and treated as the result. The result is written to a second drive, which is a repaired, replaced, or hot-spare drive for the drive being built.
Claims20
A method for reducing rebuild time on a Redundant Array of Independent Disks (RAID) device, comprising steps of:
- selecting a first stripe of said RAID device;
- enabling write-back caching on a drive being built;
- reading at least one of data or parity from at least one other drive, said at least one other drive and said drive being built belonging to a same stripe of said RAID device;
- exclusive ORing (XORing), when a RAID level of said RAID device is 5, said at least one of data or parity to obtain a result;
- and
- writing said result to a second drive, said second drive being a repaired, replaced, or hot-spare drive for said drive being built.
A method for reducing rebuild time on a Redundant Array of Independent Disks (RAID) device, comprising steps of:
- beginning or resuming a rebuild process with at least one of selecting a first stripe of said RAID device or determining a stripe of said RAID device using a last checkpoint;
- enabling write-back caching on a drive being built;
- reading at least one of data or parity from at least one other drive, said at least one other drive and said drive being built belonging to a same stripe of said RAID device;
- exclusive ORing (XORing), when a RAID level of said RAID device is 5, said at least one of data or parity to obtain a result;
- treating, when said RAID level of said RAID device is 1, said at least one of data or parity as said result;
- writing said result to a second drive, said second drive being a repaired, replaced, or hot-spare drive for said drive being built;
- and
- checking whether a checkpoint needs updating.
A method of disk write during a disk rebuild operation of a Redundant Array of Independent Disks (RAID) device where checkpoints are used, said method comprising:
- checking whether write-back is enabled on a drive;
- inquiring, when said write-back is enabled on said drive, whether a write to be written to said drive is a rebuild write;
- and
- writing, when said write to be written to said drive is not said rebuild write, said drive using a forced media access.
Dependencies are inferred from the claim text.