RAID failures may occur for several reasons:
- In case of failure of one member drive
- In case of failure of more than one member drive
- In cases unrelated to driving failure (controller problem, operation error)
In our recent case, one of the RAID 5 array drives failed. Immediately after the problem inspection, our client started to change it with the new one, hoping that RAID would continue working correctly and no data loss would occur. Unfortunately, in most cases, before changing one failed drive with another one, our clients forget to inspect healthy drives’ functionality level.
Consequently, before all data is transformed into the new drive, the second drive fails as well, which ends up with a complete array failure. Careless usage resulted in the total collapse of the RAID 5 array. Considering the capacity of RAID 5, usually, the possibility of data recovery in such cases is very low.
Fortunately, despite all the difficulties, we managed to rescue damaged drives and rebuild the array.