For all the technology in the world, it still baffles me how a technician will assume that the storage size found on the outside of the packaging of most NAS RAIDs is consistent with the actual configuration of the NAS. Assumptions are made by a technician or network engineer that will affect the safety and longevity of critical data on a shared device by using the advertised NAS storage size on the outside of the box. Truly baffling.
A short time ago I received a call from a network engineer that informed me of a NAS device he had that was down and he could not fathom why. It looked like a single drive was out of the array of a RAID 5 and the RAID had failed. In his quest for NAS RAID Recovery he pulled drives out and re-seated them, set different RAID configurations, forced the NAS share online only to reveal corrupted files. This technician did everything but a full rebuild.
In speaking with him on the phone during my intake questioning, I asked two questions. First, “What is the size of each individual drive?” Second, “What is the total storage size of the NAS?” This particular technician told me that each drive in the RAID was one terabyte and that the total storage for the RAID was 3.7 terabytes. With that drive size and storage it means that the configuration was a RAID 0. A single drive out of a RAID 0 will bring the RAID down. That being said, the client told me that the configuration was RAID 5 and that a single drive should not cause the RAID to stop functioning. All things being equal, the client is correct.
I asked the client how he knew that the NAS RAID Recovery he was attempting was a RAID 5.
He relayed to me what was on the outside of the box. As a point of reference that every technician should try not to forget is that the manufacturer will advertise the max storage size to the buyer in order to sell his product. To do that the RAID is inevitably a RAID 0.
As a rule of thumb, if you want speed and are not too concerned about speed then a RAID 0 is the way to go. If you want to be safe then use a RAID 5.