RAID 1 Recovery Following Two Failed Drives

A client recently approached us with a 2TB RAID 1 array, where both drives had failed. Thankfully, our RAID recovery team were on hand to help.

RAID, or redundant array of independent disks, combines multiple hard drives together into a single storage unit. There are multiple benefits that RAID offers, depending on the way the drives are arranged, also known as its RAID level. RAID 1, or mirroring, provides a local full-image backup of your data. Data is mirrored across both drives in the array, meaning if one drive fails, another copy of its data is stored on the other drive. Additionally, because multiple sets of heads are in operation, read speeds are improved; however, write speeds are slower. RAID 1 also essentially offers half of the total storage capacity of the array. For example, a RAID 1 array with two 2TB hard drives will only provide 2TB of storage space.

RAID 1 is RAID in one of its simplest forms, and as such, RAID recovery from a RAID 1 array is normally not any more difficult than undertaking data recovery from a single drive. Other RAID levels, such as RAID 0, stripe data across disks in the array. RAID 1 is essentially an automatic backup, and you can actually take one drive in the array and use it as a normal drive, which can’t be done with any other RAID level. So why, then, if RAID 1 provides a backup of a user’s data, do we see RAID 1 arrays in the data recovery lab? Put simply, it’s not particularly uncommon for both drives in a RAID 1 array to fail. Even worse, while both drives can fail in quick succession, particularly if they were manufacture red at the same time, or in the event of a natural disaster like a fire or flood, sometimes weeks or even months can go by before the second drive fails. That’s what happened in the case of this client. He engaged us after discovering that both drives in his RAID 1 array had failed, with the first seemingly failing months ago, leaving no evidence it had happened.

Our RAID recovery team carefully examined both drives in the array independently. In situations like this where both drives have failed and both are badly damaged, it might be necessary to recover data from a combination of the two drives. The most recent drive was identified, having suffered from damage to its read/write heads; the first drive had the same problem. The client suspects the first drive was damaged several months ago during a house move, and the second drive followed suit soon after. Thankfully, there was no damage to the drive’s platters, so after swapping the faulty heads, the drive was imaged. All of the data stored on the drive, around 1.4TB, was recovered and returned to the client. The cost of completing the recovery was provided to the client up-front in the form of a no-obligation quote and list of recoverable files.

RAID Recovery