Multi-disk high capacity storage solutions are common across all business sectors and among an increasing number of home users. At one time a RAID 5 was rare, outside of the enterprise market sector, usually only seen in IT companies with a requirement for large data volumes. With the price of data storage decreasing rapidly, while at the same time drive capacities increased sharply, it has allowed small businesses and home users to consider using a RAID 5 array.
When the RAID 5 array data configuration patent was filed in 1986, they almost exclusively used SCSI hard disk drives, which were generally seen as more reliable and capable of higher data transfer speeds. Oh the years since then the RAID data recovery engineers at DiskEng have seen a wide variety of RAID 5 arrays arrives for data recovery, ranging from simple three disk arrays through to ones containing tens of drives.
Speed with Fault Tolerance
Due to striping the data across the disks RAID 5 arrays provide an increase in read/write data transfer speeds over those seen with a single hard disk drive. The parity data is also distributed across all the drives, inducing a marginal slowdown in the write data transfer speed. This provides fault tolerance when any single drive in the array fails.
A RAID 5 array is capable of running degraded mode if only one single hard disk fails, which has resulted in some users believing that it is unnecessary to have a backup strategy in place. It was at one time seen a perfect blend of faster data transfer speeds, while providing fault tolerance.
Rebuilding RAID 5 Array
If a single drive fails in a RAID 5 array, it will continue to operate, which is often called degraded mode. Although the overall RAID will remain operational, the likelihood of a second hard disk failing shortly after is fairly high. It is therefore essential to replace the failed drive and rebuild the data onto it as soon as possible, in order to reduce the probability of such a secondary failure occurring, which would cause the RAID to go offline.
The parity which is distributed across all the drive in the array is used to calculate the data for any given sector on a single failed drive, making it possible to rebuild the data after any single drive in the array has been replaced. Although data transfer speeds have increased, so have the capacity of the drives, meaning the rebuild time is at least as long for the early RAID 5 arrays and in many cases can be considerably longer. This has resulted in the likelihood of another hard drive in the array being considerably higher, particularly for large multi-terabyte arrays across a large number of drives.
RAID 5 Array Data Recovery
If you suffer a failure of your RAID 5 array, which usually contains important data files, it is easy to panic and make a mistake, which could damage the integrity of the raw data, thereby corrupting the file system or the file contents. If your RAID 5 suffers a failure during the rebuild process, a hardware fault of the enclosure or a logical data issue, you should in all cases power the array down and then contact a data recovery company, such as DiskEng to discuss the problem with a RAID data recovery specialist.
At DiskEng we have seen a vast number of RAID 5 arrays which have suffered a variety of different failures, which has given us a high level of expertise in recovering data from this type of array, whatever the file system used on the array. We have also seen the results of the additional damage which can occur if attempts are made to resolve the issue, which tend to complicate the data recovery process and in the worst case can result in loss of data. If the data is important, you should not attempt any procedures which may result in further damage and loss of data which could put the continuity of your business at risk.
