DATA RECOVERY RAID 5

Data recovery on a RAID 5 system is facilitated by its redundancy system in the event of the loss of a hard disk in the array. In the event of failure, a logical operation based on parity blocks enables lost data blocks to be regenerated on each stripe. Data availability remains high, as the system is able to operate with a missing disk or during “parity recalculation” and data reconstruction.

Despite its fault tolerance, RAID 5 cannot withstand the loss of more than one hard disk at a time. The probability of simultaneous failures can rapidly increase, particularly during the rebuild time, which places intensive demands on the other disks in the cluster. It can also happen that parity blocks or corrupted sectors on functional disks are not detected until another disk has failed completely. Strip reconstruction is then compromised, if not impossible.

When several disks in a RAID 5 system appear to be faulty, an initial analysis can be carried out to determine whether a single corrupted block is at the root of the problem. A partial reconstruction of the data can then be envisaged, before embarking on more extensive recovery procedures.

But when the parity algorithm does not allow reconstruction, the complex architecture of RAID 5 (disk order, layout of data and parity blocks, etc.) requires theexpertise and intervention of a laboratory.