With RAID arrays increasing in size it has become more common to combine two RAID levels, such as RAID 5 and RAID 0. This takes advantage of the distributed parity of the RAID 5 level with the extra speed gained by using the data striping of RAID 0.
At least 6 hard disk drives are required for this configuration, providing a good compromise between added redundancy and data transfer speeds. This allows for the possibility of the array continuing to work in degrade mode following two hard disk drive failures, as long as they are not located within the same RAID 5 array.
When a drive fails, it is important that it is replace as soon as possible and a rebuild initiated, as the risk of a second failure occurring within the same RAID 5 array increases the longer it operates in degraded mode. For this reason, it is also important that a backup strategy is put in place to guard against such a failure, as the data is at risk until the rebuild has been completed.
Our engineers have seen many examples of RAID 50 arrays arrive for data recovery, some containing tens of hard disk drives, used in NAS and SAN RAID systems. These can be extremely complex arrays, sometimes containing multiple file systems, which in the case of a SAN may be spread across several non-contiguous areas of the array.
RAID 50 arrays require an in-depth knowledge of the underlying RAID architectures and file systems. In some cases, it is only possible to determine the order of the hard disk drive in the RAID scheme by using the data structures present in a file system.
Most RAID 50 arrays arriving for a data recovery are the result of physical failure, although some rare instances of logical problems have also been seen. Most physical failures are the result of multiple hard disk failures, although a failure of the RAID enclosure can also result in the configuration being lost, which requires data recovery to access the files.
Whatever the failure and size of the RAID 50 array, DiskEng have a RAID data recovery solution to suit your requirements. Call DiskEng now to discuss your RAID 50 data recovery requirements.