RAID & NAS Data Recovery
RAID Storage (which includes most Network Attached Storage (NAS) devices can prove problematic when it comes to data recovery. In the most common configurations, RAID allows for “n -1”, where n is the number of disks in the array, the loss of one disk (-1) does not cause a failure. When one disk fails, it is normal practice to simply replace the failed disk and the array will rebuild itself while remaining online.
Unfortunately it doesn’t always work that way as single points of failure do exist in RAID systems and NAS devices, indeed it is possible to have more than one disk fail shortly after one another or for a disk to fail during the rebuild process.
For example, single points of failure can be the RAID Controller or the RAID Software which if malfunction or become corrupt can cause a catastrophic failure – RAID is not a backup!
RAID Recovery Process
Most RAID & NAS recoveries involve the same processes, except where they are configures as RAID 0 or JBOD (Just a Bunch Of Disks).
The first step is to evaluate the condition of each member disk from the array, accounting for any hot spares that may be reserved for use in the event of a disk failure. Following evaluation, each disk must be imaged to another disk (this is to avoid recovering from the original media), of course any problems with the disks must be put right first.
During the evaluation, repair and imaging process, we will establish which disk failed most recently – if 2 disks have failed the one that failed last will hold the most up to date data – we’ve seen instances where disks have failed several months apart so it is important to ensure that we have the most recent and therefore most relevant disks for recovery.
Now we have disk images of either all member disks or at the very least just one missing disk, the next task is to determine the RAID configuration and rebuild the volume in software. Once this is complete the data can be extracted to another device.
RAID Recovery is complex and can be time consuming – especially where one or more disks require head replacements. We therefore recommend that the sooner you get the disks to us, the sooner you’ll have your data back.