Recover hardware RAIDs

A hardware RAID requires a RAID controller. The RAID may fail when the controller or a disk fails.

First determine if the RAID is broken. If not, do not use the Advanced Volumes command. The disk can be scanned as an ordinary disk.

If the RAID is broken, proceed as follows:

1. Immediately shutdown the computer and turn off power to the disks to protect the data.
2. Carefully label the disks as to their order in the RAID. The order is critical during reconstruction.
3. Connect the disks to an ordinary disk controller as independent non-RAID, non-boot disks. If the RAID controller allows disabling of RAID function, the same controller can be used with RAID disabled. Be careful not to let the RAID controller initialize the disks and destroy the data permanently.
4. Start Windows® and use Disk Management to verify that the disks are displayed individually.
5. In File Scavenger® select Quick scan then click File, Advanced Volumes to reconstruct the RAID.

Example 1: RAID is damaged but not broken.

Consider the following configuration:

Disk 1 is made up of 3 36-GB disks connected to a hardware RAID controller. Parity takes up one drive; therefore the size of the RAID is only 2 x 36 GB = 72 GB. Windows® sees a 72-GB disk. The RAID controller manages the component disks.

Suppose the computer is restarted after power loss and Disk Management shows the following:

In this case, the RAID is corrupted but not broken and can be scanned as an ordinary disk.

In Look in, choose Disk 1. Select a scan mode and click Scan.

Example 2: The RAID is broken

Consider the same configuration as in Example 1. Suppose when the computer is restarted, the RAID controller reports an error. Only Disk 0 can be seen in Disk Management, as follows:

Do not reconfigure the RAID in the BIOS or by using a vendor-supplied tool. When a RAID 5 is initialized, all existing data may be destroyed.

To reconstruct the RAID with File Scavenger®, the disks must be connected individually as ordinary non-RAID, non-boot disks to a computer running XP or later.

In RAID 0, all disks must be connected. In RAID 5 or RAIDZ1, one disk can be missing. In RAID 6 or RAIDZ2, two disks can be missing. The parity information on the remaining disks is sufficient to regenerate the missing data.

Suppose that all three disks have been connected and Disk Management displays the following:

Proceed as follows:

1. Select Quick (preferred) or Long scan.
2. Click Advanced Volumes.
3. Choose RAID5 for Volume type.
4. Specify 3 drives.
5. Select a parity rotation.
6. Select a Block size.
7. Select a Parity delay. The value is 1 for most RAIDs, and 16 for some HP RAIDs. Click Next.
8. In the next dialog, select the disks in their correct order in the RAID. Assume the order is Disk 1, 2 and 3 in this case, select them in that order.
9. For each disk, choose the RAID partition. You can also choose Entire disk and specify the First sector value.
10. Specify the amount of disk space per disk allocated to the RAID. You should almost always use the default value which is the entire disk. Click Finish.
11. Click Scan to start the scan.
12. Specify the volumes for scanning. If there is no valid volume, you will need to use the Long scan.
13. Choose to skip deleted files.
14. When the scan is complete, select files and save them to another drive.

Note that if the recovered files are gibberish, the following settings may be incorrect:

• Block size.
• Parity rotation.
• Disk order. (The disks may have changed position.)
• First sector values.

Determining the correct RAID settings is the most difficult aspect of RAID recovery.
For quick and guaranteed results, use our fee-based RAID analysis service.