AMCC 3ware 9000 Series, User Manual

Page: 137 / 202

Rebuilding Units
www.3ware.com 131
an 8-drive configuration, up to four drives can be rebuilt. In a 12-drive
configuration, up to six drives can be rebuilt.
Note : If both drives in a RAID 10 mirror set are faulted, the data is
not recoverable. Up to half of the drives in a RAID 10 unit can
become defective and still have the user data retained, as long as
the failed drives are only half of each mirrored pair.
A RAID 50 unit can also sustain multiple drive failures, as long there is only
one failed drive in each RAID 5 set.
When a RAID 5 is running in Degraded mode, the missing data is
reconstructed from all non-degraded drives.
Note:
If a rebuild fails, check the Alarms page for the reason. If
there was an ECC error on the source disk, you can force the
rebuild to continue by checking the Overwrite ECC Error policy on
the Controller Settings page in 3DM and then running Rebuild
again. This will cause uncorrectable blocks to be rewritten, but the
data may be incorrect. It is recommended that you execute a file
system check when the rebuild completes.
Rebuilding a Unit Through 3DM
When a drive on a unit degrades, you replace it with an available drive and
then rebuild the unit.
To rebuild a unit through 3DM
1 If necessary, add a new drive to be used to replace the failed drive. (For
details, see “Adding a Drive through 3DM” on page 110.)
2 In 3DM, choose Management > Maintenance .
3 In the Unit Maintenance section of the Maintenance Page, select the
degraded unit and click the Rebuild Unit button.
4 When a dialog box displays available drives, select the drive you want to
replace the degraded drive and click OK.