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Recovering Software-Based RAID

A software-based RAID 0 (also called a striped volume) or RAID 5 is implemented in Windows and can be created with Disk Management (in Computer Management). The component disks are connected to the computer as ordinary disks and can be seen in Windows Disk Management as individual disks.

Example 1: Recover files from a broken software-based RAID 5

Consider a computer with the following configuration:

Disk 0: drive C: (boot disk).
Disk 1: 36 GB, all allocated to a RAID 5.
Disk 2: 36 GB, all allocated to a RAID 5.
Disk 3: 36 GB, all allocated to a RAID 5.

The RAID 5 is configured as drive D: with 72 GB which is the total size of three disks less one disk for parity.

Assume sudden power loss occurs. When the computer is rebooted, the RAID is broken. Disk Management displays the following:

Disk 0: Drive C: (boot disk).
Disk 1: 36 GB of unallocated space.
Disk 2: 36 GB of unallocated space.
Disk 3: 36 GB of unallocated space.
Drive D: has disappeared.

Use the following reconstruction procedure:

  1. Select Quick Mode.

  2. Click Advanced Volumes. Choose Striped volume.

  3. Check With parity.

  4. Specify 3 disks.

  5. Assume the RAID was created on a Windows® Server 200X computer, for parity rotation select Backward, symmetric. Click OK.

  6. In the next dialog, select the disks in their correct order in the RAID. The disk order in a software-based RAID may not follow the disk numbers and can only be determined with certainty by analyzing the disk contents. With 3 disks there are 6 possible orders to try. Alternatively, you can use our fee-based RAID analysis service.

  7. For each disk, choose the RAID partition. You can also choose Entire disk and specify the First sector value.

  8. Specify the amount of disk space on each disk allocated to the RAID. This value must be less than or equal to the Maximum value shown to the right. In this example, the default value is used because the entire disk is allocated to the RAID.

  9. For RAID 0, the Total volume size is the disk space For each disk times the number of disks. For RAID 5, parity overhead consumes one disk; therefore the total size is this value times the number of disks less one. Click OK.

  10. In the Striping block size dialog, select 64 KB as the block size. The Data blocks per parity group is always 1 for software-based RAID. Click OK.

  11. Click Scan to start the scan.

  12. Choose to skip deleted files.

  13. When the scan is complete, select files and save them to another drive.

Note that if one disk is missing, select the keyword Missing in its place.

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