# Rebuilding a hot-swap drive

A hot-swap rebuild refers to a rebuild operation that is started by the controller when it detects that a drive that is part of an array and in the defunct state has been removed and reinserted on the SCSI cable or backplane. The reinsertion of the physical drive, whether it is the same drive or a new drive, will trigger the controller to start the rebuild operation. During the rebuild operation, the drive being rebuilt is in the rebuild state, and the logical drive remains critical until the rebuild operation has been successfully completed.

On most servers, when a hot-spare drive is available, the rebuild operation begins automatically without the need to replace the failed drive. If more than one drive fails within the same array, no rebuild takes place. If multiple drives fail in separate arrays (one physical drive per array), the controller initiates a rebuild operation for the logical drives within the array containing the first failed physical drive. This rebuild operation is performed on the first hot-spare drive of sufficient size to become a valid member of the array.

Complete the following steps to start a hot-swap rebuild:

1. Without removing the drive completely, gently remove the physical drive from the server, using the handle of the hot-swap tray. If necessary, refer to the documentation that comes with your server for information about removing a physical drive.
   Attention: When power is removed from a hot-swap drive, the drive immediately parks the heads, locks the actuator in the "landing zone," and begins spinning down. However, the spinning down of the disk might require up to 20 seconds after power is removed. Do not move the drive while it is spinning down. Moving the drive while it is spinning down might damage the drive.
2. Wait 20 seconds to allow the physical drive to completely stop spinning.
3. If you are certain there is nothing wrong with the physical drive you removed, gently reinstall the drive into the server. Make sure the drive is completely installed in the backplane connector.

   Otherwise, replace the physical drive with a new drive that is the same size (or larger) and continue with the rebuild operation.

   Notes:
     1. If multiple drives fail in separate arrays (one physical drive per array), replace each defunct physical drive. If multiple physical drives fail at the same time within the same array, contact your service representative.
     2. Although it is possible to rebuild a defunct physical drive to an online physical drive that is defective, avoid doing so.

## More information

- Rebuilding a defunct drive
- Recovering from defunct drives
- Manually rebuilding a defunct drive
- Changing the rebuild rate (action)
- Unblocking a logical drive (action)

Glossary | Contents

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