Friday, October 28, 2016

RAID 5 recovery

RAID 5 recovery


RAID 5 recovery

In order to recover RAID 5 first you need to determine RAID 5 configuration parameters and then recover data.
RAID 5 array configuration consists of:
  • how many disks were in the RAID 5
  • what was the disk sequence
  • what block size was used in the array
  • at what offset the array data began
  • what the parity pattern was used in the RAID5
  • in you deal with RAID 5 with delayed parity you need to know the parity delay pattern as well
  • in case of RAID5E and RAID5 EE you need to know how spare blocks are located on the array
All these parameters can be determined both manually and automatically. However, if you decide to recover the RAID 5 configuration manually you should be aware that this will be a very long and tedious process which requires special techincal skills.

Manual RAID 5 recovery

The information on how to determine the array parameters manually is given on a RAID 0 recovery page. Unlike RAID 0, RAID 5 is a redundant array and stores the parity data. You need to determine the parity position and rotation as well to get the full configuration of your array.
How to determine parity position
The parity placement is controlled by two parameters, parity position and rotation as illustrated below. To determine the parity position you should look over each of array blocks. A block that looks most unlike data is the parity block.
RAID 5 parity placement, sample 1 RAID 5 parity placement, sample 2

RAID 5 recovery with software

If the manual option seems too complex and time-consuming, try ReclaiMe Free RAID Recovery software.
  1. Download and launch ReclaiMe Free RAID Recovery tool.
  2. If it is needed, open or create disk image files of the RAID 5 member disks using the Disks button.
  3. Select all the available member disks and click Start RAID 5. You should select at least two disks. Note that ReclaiMe Free RAID Recovery software is capable of recovering a RAID 5 with one disk missing.
  4. The RAID 5 recovery finishes when either Scan or Confidence progress is completely filled.
  5. When the RAID 5 configuration parameters are restored, you should select one of the following:
    • Run ReclaiMe to recover data. If ReclaiMe data recovery software has been already installed on the computer, then it is launched in RAID recovery mode and displays the partitions on the array. If you do not have ReclaiMe, you will be offered to download ReclaiMe data recovery software.
    • Save layout to the XML file. Save the recovered array parameters to the file in XML format. Note that you can open this file in ReclaiMe and start to recover data off the array using ReclaiMe RAID recovery mode.
    • Use with other data recovery software. Provides step-by-step instructions on how to transfer the recovered parameters to certain well-known data recovery tools. Note that the instructions are created for each particular case of RAID and you should follow them exactly. Should the need arise, the instructions can be copied to the clipboard using Copy to the clipboard button.
More info on what to do before you start to recover your RAID 5 and more detailed instructions are provided on the how to recover RAID tutorial page.
If you want to try something else, there are other tools capable of automatically recovering RAID 5 on the market (check the RAID recovery software comparison). These software utilize different algorithms (not necessary such as described above) and usually such tools are relatively expensive. We offer a fully automated and free solution for the RAID 5 recovery situations. Our software ReclaiMe Free RAID Recovery determines the array configuration parameters for RAID 0, RAID 01/10, and RAID 5 using only the data contained on the member disks. Just download ReclaiMe Free RAID Recovery then select all the available member disks (dont forget to connect them to the PC separately), start RAID 5 recovery and get the recovered RAID 5 configuration. More instructions on how to recover RAID tutorial page.

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