## Replacing and rebuilding a drive

When a hard disk drive goes defunct, a Rebuild operation is required to reconstruct the data for the device in its respective disk array. The ServeRAID controllers can reconstruct RAID level-1 and RAID level-5 logical drives, but they cannot reconstruct data stored in RAID level-0 logical drives. To prevent data integrity problems, the ServeRAID controllers set the RAID level-0 logical drives to blocked during a Rebuild operation. After the Rebuild operation completes, you can unblock the RAID level-0 logical drives, and access them once again. But remember, the logical drive might contain damaged data.

To perform a Rebuild operation:

1. Click the defunct physical drive from the Main Tree.
2. Click Actions --> Replace drive and rebuild.
3. Click OK to use the same drive slot and SCSI ID if you have physically replaced the defunct drive with a new drive.

Once you have replaced the defunct drive with a new drive, the ServeRAID Manager automatically starts rebuilding the drive. The Manager displays a progress indicator in the status bar.

Use this action on defunct drives that are part of a critical logical drive. If the defunct drive is not part of any critical logical drives, but is in the array, you cannot use this action. Use Set drive state to online instead.

Notes:

- The ServeRAID controller can perform only one Rebuild operation at a time.
- If the array contains a critical logical drive, the Rebuild operation changes the hard disk drive state from defunct to Rebuild. After the Rebuild operation completes, the hard disk drive state changes from Rebuild to online. (If you rebuild to a ready drive, the defunct drive is removed from the disk array and becomes a defunct hot-spare.)
- The hard disk drive being rebuilt must be the same size or larger than the failed drive.
- If a hot-spare drive is available, a Rebuild operation will start automatically.
- If multiple hot-spare drives are available, the ServeRAID controller searches all the drives on each channel for a hot-spare drive of the appropriate size. The first appropriate hot-spare drive found enters the Rebuild state.