To bring a basic disk back to an online state

1. Repair any disk or controller problems, and make sure that the disk is turned on, plugged in, and attached to the computer.
2. Use the Rescan command to rescan all the devices on the SCSI bus to bring the disk back online.

   Select Rescan from the Actions menu, or right-click the StorageAgent node in the tree view to get a context menu and select Rescan from that menu. If you have a lot of devices on the computer's SCSI bus, the rescan of the bus may take some time.

3. If a disk comes back online after rescanning, check to see whether its volumes are healthy.

   If they are not, you need to bring the volumes back to a healthy state.

4. Run Chkdsk.exe to make sure that the underlying data on the disk is not corrupted.

   Even if the disk and volumes come back online, it is important to check whether the underlying data is intact.

   To run Chkdsk, open a command prompt window and enter the following command:

   chkdsk x: /f

   where x is the drive letter of the volume you want to check. The /f option tells Chkdsk to fix any errors it finds. If the /f option is omitted, Chkdsk operate in a read-only mode.

   If the data is corrupted, you need to replace it with data from backup storage.