System and method for reducing unrecoverable media errors in a disk subsystem
View Patent ↗A system and method for reducing unrecoverable errors in a disk drive by under-taking an aggressive reassignment of slow-reading or currently recoverable-but-erroneous sectors to the spares pool is provided. A recovered error is treated by the system operating system as a fatal error and thereby the sectors involved are reassigned to the spares pool immediately. Reassignment is recommended by a reassignment utility at the disk interface level, which passes a status up to the RAID subsystem by which reassignment is performed. In order to prevent a double-disk panic, the RAID subsystem is instructed to ignore reassignment recommendations of this type (e.g. reassignment of recoverable errors) if the RAID group is currently operating in a degraded state. However, if the RAID group is undegraded, then immediate assignment of the sectors encountering the recoverable error is undertaken.
1. A method for handling a disk error, comprising:
receiving, in response to an I/O operation, a status signal indicating a disk error;
determining if a RAID group containing the disk is in a degraded state;
if the RAID group is not in the degraded state, reassigning the I/O operation to a spare sector; and
if the RAID group is in the degraded state:
not reassigning the I/O operation to the spare sector, and
storing the I/O operation in a log to reassign to the spare sector at a future time.
2. The method of claim 1 , wherein the RAID group is in the degraded state after a disk failure occurs to another disk within the RAID group but before reconstruction has completed of the disk failure.
3. The method as set forth in claim 1 wherein the spare disk sector is one of a plurality of spare disk sectors included in a spares pool on the disk and is mapped via a defect list associated with the disk.
4. An apparatus for handling a disk error, comprising:
means for receiving, in response to an I/O operation, a status signal indicating a disk error;
means for determining if a RAID group containing the disk is in a degraded state;
if the RAID group is not in the degraded state, means for reassigning the I/O operation to a spare sector; and
if the RAID group is in the degraded state:
means for not reassigning the I/O operation to the spare sector; and
means for storing the I/O operation in a log to reassign to the spare sector at a future time.
5. The apparatus of claim 4 , wherein the RAID group is in the degraded state after a disk failure occurs to another disk within the RAID group but before reconstruction has completed of the disk failure.
6. A system for handling a disk error, comprising:
a storage adapter for receiving, in response to an I/O operation, a status signal indicating a disk error;
a mechanism in the storage layer for determining if a RAID group containing the disk is in a degraded state, and if the RAID group is not in the degraded state, reassigning the I/O operation to a spare sector; and
if the RAID group is in the degraded state, the mechanism is further configured to:
not reassign the I/O operation to the spare sector, and
store the I/O operation in a log to reassign to the spare sector at a future time.
7. The system of claim 6 , wherein the RAID group is in the degraded state after a disk failure occurs to another disk within the RAID group but before reconstruction has completed of the disk failure.
8. The system as set forth in claim 6 wherein the spare sector is one of a plurality of spare sectors included in a spares pool on the storage device and is mapped via a defect list associated with the storage device.
9. A computer readable media, comprising:
the computer readable media containing instructions for execution on a processor for the practice of the method for handling a disk error, comprising:
receiving, in response to an I/O operation, a status signal indicating a disk error;
determining if a RAID group containing the disk is in a degraded state; and
if the RAID group is not in the degraded state, reassigning the I/O operation to a spare sector
if the RAID group is in the degraded state:
not reassigning the I/O operation to the spare sector, and
storing the I/O operation in a log to reassign to the spare sector at a further time.
10. The computer-readable medium as set forth in claim 9 wherein the spare disk sector is one of a plurality of sectors included in a spares pool on the disk and is mapped via a defect list associated with the disk.