“When our NAS failed during a rebuild, it was panic stations, as it contained our latest research data, required for imminent publication. Many thanks the assurances and successful recovery of all the data. Professional and swift turnaround.”
Bryan Arnold, FSD Research, Epsom
A NAS server array, which had failed during a rebuild, containing four 2TB Western Digital hard disk drives arrived at our laboratory from Epsom. After examining the drives, no fault with the hardware or the electronics on the drive controller board. When our hard disk data recovery specialists imaged the four drives, they encountered a number of unreadable bad sectors on three of the four drives.
Hard disk drives have an inbuilt capacity to deal with bad sectors on a drive, maintaining a list of swapped out sectors. This list is however only a finite size, and over time will become exhausted, leading to bad sectors becoming apparent to the operating system, or RAID controller. With a set of hard disk drive maintained in the same environment, and sourced from the same supplier, it is not unusual for two or more drives to fill their spare sector list at a similar rate.
The RAID configuration being used was RAID 10 which is a striped mirror set, which means that the bad sectors on the damaged drives will only be lost if the same sector on a mirrored pair are unrecoverable. A virtual RAID set was created, revealing only two sectors which were unrecoverable. Fortunately these were affecting non-critical system areas of the file system, allowing for a full recovery of the 2.3TB of data files to be returned to the client.