3Ware 9550SXU16MLB10 User Guide - Page 137

Rebuilding Units 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. www.3ware.com 131