QueTek
  
Secure Site  
Reconstructing a broken RAID
 
It is important to understand the differences between rebuilding (or repairing) and reconstructing a RAID. Repairing a RAID is a risky and irreversible procedure. One uses utilities (supplied by the RAID controller manufacturer) to restore it to working order by modifying the member disks. Should a mistake be made or an unexpected error occurs, one may not be able to go back to the starting state and data may be lost permanently.

On the other hand, reconstructing a RAID is a safe, read-only and repeatable procedure except for normal disk tear and wear. In this procedure, you use File Scavenger® to emulate a RAID controller. Data blocks are extracted from the individual member disks, assembled into the original data and copied to a new disk. No changes are made to the original disks. If a mistake is made or an error occurs, the procedure can be repeated.

You can use File Scavenger® to reconstruct a RAID, either by yourself or by using our money-back guarantee RAID recovery service. When doing it yourself, successful recovery depends on your knowledge of the RAID settings and the complexity of the RAID configuration. When using our service, successful recovery is almost certain except when the member disks have been changed so much that there is insufficient information to reconstruct the original data.

The following table provides estimates for your chance of success in a few typical scenarios, assuming the member disks have not been changed beyond recovery.

Successful RAID recovery using File Scavenger®
RAID Settings Do-it-yourself With our assistance (info)
Implementation Level Number of disks Success rate Cost(1) Time Success rate Cost(2) Time
Software RAID 0 2 90% $ 89.00 1 day 95% ~$ 450.00 1 day
3 75% $ 89.00 1 day95% ~$ 550.00 1 day
RAID 5 3 75% $ 89.00 1-2 days 95% ~$ 700.00 1 day
4 40% $ 89.00 1-3 days 95% ~$ 800.00 1 day
Hardware RAID 0 2 80% $ 89.00 1 day 95% ~$ 450.00 1 day
3 60% $ 89.00 1 day 95% ~$ 550.00 1 day
RAID 5 3 40% $ 89.00 1-3 days 95% ~$ 700.00 1 day
4 25% $ 89.00 2-4 days 95% ~$ 800.00 1 day

Notes:
(1): For a File Scavenger® license.
(2): For a File Scavenger® license and our RAID recovery service.

RAID reconstruction consists of the following steps
  1. Optionally backup the member disks.
  2. Reconfigure the member disks as stand-alone disks.
  3. Locate a new disk to copy data to.
  4. Determine the RAID settings.
  5. Use File Scavenger to reconstruct the RAID and recover data to the new disk

Backup the member disks

Weigh the benefits versus costs of creating disk image files of the member disks as a backup copy. This will take more time and require more new disk space. The main benefit is to have a duplicate copy of each disk in case it fails. Note that if you have a broken RAID 5 in which all the member disks are good, you are already protected from the failure of one disk.

Reconfigure the member disks as stand-alone disks

The RAID member disks must be reconfigured as stand-alone disks so that the original data can be reconstructed. They must be concurrently installed on a computer running Windows® XP or later. You can connect them to ordinary disk controllers. Many RAID controllers also allow attached disks to be configured as stand-alone disks.

To verify the configuration, run Windows Disk Manager to see if all disks are displayed separately.

Use File Scavenger to reconstruct the RAID

The reconstruction procedure depends on the RAID implementation and level as follows: