IBM ServeRAID-4 Ultra160 Series, User Reference

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Rebuilding a defunct drive
A physical drive is marked defunct when there is a loss of communication between
the controller and the physical drive. This can be caused by any of the following:
v
An improperly connected cable, physical drive, or controller
v
Loss of power to a drive
v
An improperly assembled SCSI channel in an unsupported configuration
v
A defective cable, backplane, physical drive, or controller
v
Connecting unsupported SCSI devices (such as tape drives or CD-ROM drives)
to the same SCSI channel used for an array.
In each case, after the communication problem is resolved, a rebuild operation is
required to reconstruct the data for the device in its disk array. The ServeRAID
controllers can reconstruct RAID level-1 and RAID level-5 logical drives. They
cannot, however, reconstruct data stored in RAID level-0 logical drives because
RAID level-0 is not redundant. If an array contains only RAID level-0 logical drives,
the logical drives in the array are marked offline and the logical drives might contain
damaged data. You cannot rebuild the logical drives. You must correct the cause of
the failure, or replace the physical drives and restore your data.
To prevent data-integrity problems, the ServeRAID controllers set the RAID level-0
logical drives in the affected array to blocked during the rebuild operation for RAID
level-1 or RAID level-5. After the rebuild operation completes, you can unblock the
RAID level-0 logical drives, and access them once again. Remember, however, that
the RAID level-0 logical drives might contain damaged data.
Note: For logical drives in an IBM ServeRAID Cluster Solution:
v
Because shared logical drives can have only one logical drive for each
array, blocking a RAID level-0 logical drive during a rebuild operation does
not apply to shared logical drives.
v
Because non-shared logical drives can have more than one logical drive
for each array, blocking a RAID level-0 logical drive during a rebuild
operation does apply to non-shared logical drives.
Recovering from defunct drives
If multiple physical drives fail at the same time in the same array, or if the defunct
drives are not part of an array, contact your IBM service representative.
If a physical drive fails in an array or multiple physical drives fail in separate arrays
(one physical drive per array), do the following:
1. Replace each defunct physical drive. The ServeRAID controller starts the
rebuild operation when it detects the removal and reinsertion of a drive that is
part of an array.
2. If a rebuild operation is in progress, wait until the rebuild is complete. Otherwise,
go to step 3.
Note: If you are replacing multiple defunct drives, you must wait for each
rebuild operation to complete before starting subsequent rebuild
operations.
3. Verify the cables, physical drives, and controllers are installed properly.
4. Attempt to rebuild the defunct physical drive by performing a hot-swap rebuild.
Refer to “Rebuilding a hot-swap drive” on page 148 for instructions.
Chapter 18. Solving ServeRAID problems
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