Rapid regeneration of failed disk sector in a distributed database system
First Claim
1. A method for operating a Redundant Array of Inexpensive Disks (RAID) to recover from read errors comprising:
- in a disk controller,detecting that a read error has occurred in a sector associated with a particular Logical Block Address (LBAi) in a primary disk portion;
reporting an unrecoverable read error at LBAi;
remapping the sector originally associated with the LBAi for which the read error occurred to a replacement sector;
in a RAID controller,receiving a report of an unrecoverable read error at LBAi;
retrieving data from a mirror disk portion associated with the primary disk portion that contains LBAi; and
writing the same data thereby retrieved to the LBAi on the primary disk portion for which the error was specified.
4 Assignments
0 Petitions
Accused Products
Abstract
A technique for read error failover processing in a mirrored disk system such as a Redundant Array of Inexpensive Disks (RAID) system, where individual disk units perform Logical Block Address (LBA) remapping. A read error causes a disk controller to report an “unrecoverable” read error to a RAID controller. After receiving this report of an unrecoverable read error, rather than simply switching over to a mirror, the RAID controller first checks to see whether the disk that caused the error can successfully reassign an LBA. In particular, the RAID controller can retrieve the data that was associated with the failed LBA from the mirror, and then write that data to the offending disk. The disk controller for that disk will then perform its standard LBA remapping, and write the data to a new, good sector. Only if this process does not succeed is the offending disk then treated by the RAID controller as having failed sufficiently to require failover to the mirror.
63 Citations
16 Claims
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1. A method for operating a Redundant Array of Inexpensive Disks (RAID) to recover from read errors comprising:
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in a disk controller, detecting that a read error has occurred in a sector associated with a particular Logical Block Address (LBAi) in a primary disk portion; reporting an unrecoverable read error at LBAi; remapping the sector originally associated with the LBAi for which the read error occurred to a replacement sector; in a RAID controller, receiving a report of an unrecoverable read error at LBAi; retrieving data from a mirror disk portion associated with the primary disk portion that contains LBAi; and writing the same data thereby retrieved to the LBAi on the primary disk portion for which the error was specified. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for operating a Redundant Array of Inexpensive Disks (RAID) to recover from read errors comprising:
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a disk controller, connected to a primary disk portion, the disk controller for detecting that a read error has occurred in a sector associated with a particular Logical Block Address (LBAi) in a primary disk portion, and in response thereto, reporting an unrecoverable read error at LBAi, and further for remapping the sector originally associated with the LBAi for which the read error occurred to a replacement sector; a RAID controller, connected to the disk controller, and for receiving the report of an unrecoverable read error at LBAi therefrom, and in response thereto, for retrieving data from a mirror disk portion associated with the primary disk portion that contains LBAi, and then writing the same data thereby retrieved to the LBAi on the primary disk portion for which the error was specified. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification