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Guide >> How to... >> RAID 0 - RAID 5 Data Recovery

Virtually Reassemble a Deleted or Damaged RAID.
RAID 0 - RAID 5 Data Recovery

There are many reasons for a Redundant Array of Independent Disks (RAID) system to fail (RAID controller failures, software RAID emulator errors, etc.). Active@ File Recovery provides an easy way to assemble array disks together and make damaged or deleted data accessible.

You can combine a set of disks that were previously used as a part of a RAID system in a temporary (virtual) disk array. With this a virtual configuration, it enables performing all drive file recovery operations as though working with regular drives.

It is important you specify the parameters of the RAID system that existed before the fault so that the same system can be virtually reassembled.

It is also important to list the disks in the correct order when making a virtual disk array. In most cases, the correct order is unknown. The only way to discover the correct order is to try all available combinations until you reach the one that works. If you are dealing with only two disks, it is simple. You have only two ways to arrange the order. If there are three disks, you must try a maximum of six combinations. If there are four disks, 24 combinations, and so on...

Each time you try a combination, write down the order you are trying.  Click OK to accept the configuration.  Check the results by trying to access and scan the newly-created virtual RAID that is added to the list of Local System Devices. If you don't see your data or if there was an error during the virtual array creation, mark this one as a failure and try another order of disks in array.

 

To virtually reassemble a RAID system:

  1. To open the RAID Reassembly dialog box, do one of the following:
    • Click RAID on the toolbar
    • In the Tools menu, choose RAID...

     

  2. To choose a supported RAID type, in the Virtual Volume Type area, choose one of the following:
    • Stripe Array (RAID-0) - Data located in stripes (blocks of size 32KB, 64KB, 128KB, etc.) distributed between two or more drives
    • Mirror Array (RAID-1) - Data on two disks is identical - provides complete data duplication (or mirroring)
    • RAID-5 Array - Data located in stripes distributed between two or more drives with parity control
    • Span Array - Data located contiguously on one disk then on another disk, and so on...
  3. To select disks from a list to create a virtual disk array:
    1. In the Available Disks list, select a disk name.
    2. To add it to the Selected Disks list, click Add.
    3. Repeat steps a. and b. for every disk in the original array. If one of the disks is physically damaged which is not accessible, and you have selected RAID-0 or RAID-5 in step 2, add the Damaged Device place holder (from the Available Disks list) instead of the named damaged disk.
    4. To change the order of disks in the Selected Disks list, select a disk name and click Up or Down to change its position in the list.
  4. In the Options area, indicate the size of the stripe block by typing in the size of the block in kilobytes in the Stripe Block (RAID0 and RAID5) field. This is applicable only to RAID-0 and RAID-5 arrays. Standard values are 32Kb, 64Kb, 128Kb, 256Kb. If you are not sure, try each size until you get the correct one.
  5. In the Disk Area to Use in RAID in Sectors area, indicate the offset and the size of the device, measured in sectors (each sector is 512 bytes). Type in the values for the Offset and Size. In most cases, the default values are acceptable. Some RAID controllers only use part of the disk surface. For example, a HighPoint 370 uses the first 100 sectors on the first drive for its own system information. In this case, specify the offset as 100 sectors.
  6. Click OK.

A new Virtual Disk Array device node will appear in the Local System Devices list.  You may treat this new node and its contents in the same way you treat other device nodes in the list. You may follow the same steps to scan the node, and then search for files/folders to be recovered.

Note

When dealing with Span Arrays, you may get the size of a Damaged Disk a couple of ways:

  • Go to the hard drive manufacturer's web site and look for the model.
  • Look for the device geometry label on the top of the physical drive. If you find it (it is not always there) you can multiply the parameters C*H*S (Cylinders * Heads *Sectors per Track) to get the number of sectors. For example, Samsung SW0212A has the following: CYL 4092, HD 16, SEC 63, 2.1GB. Multiply 4,092*16*63 to get 4,124,736 sectors. To calculate the disk size, multiply 4,124,736*512 = 2,111,864,832bytes = 2.1GB.  We just confirmed the size 2.1GB. The size is marked on drive label and that proves that our calculations are correct.


 
See Also

Performing Extended Device Scan, Searching for Deleted Files and Folders

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