An Overview of What is Required for a RAID 5 Recovery
This is a quick summary of the tasks required to recover the data from an inaccessible RAID 5 volume. It is only necessary after user access to the data stored has been lost. If a failure has occurred with one of the drives only then data access is still available and as long as you back up your data now you will have no requirement for RAID 5 data recovery. The first task is to clone all of the discrete hard drives that comprise your RAID array. All subsequent work should then be carried out on those clones. Never work directly on the failed drives. If these drives fail while you are carrying out the RAID analysis on them then the job is over and your data is beyond all help. It is likely that one or more of these drives may have a problem that prevents cloning (at this point you need the help of data recovery experts). You will be able to recover at least some of the RAID data in the event that one, but not more than one of the failed drives cannot be accessed. A RAID 5 volume can suffer one discrete drive failure and still allow access to all of the data. It does this through “parity” which is a means of being able to infer what a missing piece of data was based on what the detectable data is. Next you will need to determine the basic RAID characteristics, that is data stripe size, drive order and parity arrangement (again if you don’t know how to deduce these then it is time to hand to job to the professionals). Finally you will need to re-build the RAID volume, there are many suitable software tools for doing this but all require a good understanding of RAID structure before they can be used effectively.