When searching for Network Storage solutions, often people look at price and wonder why they should spend more money for NAS RAID instead of just a single hard drive in the NAS device.
The NAS device may or may not be backed up, I would suggest it most likely is not. If the network storage device itself is for backup, maybe you do not need RAID1, RAID5, or RAID6 (or X-RAID or X-RAID2 in a ReadyNAS unit) to protect your data.
If the NAS is just for backup, and not archival backup, losing the only drive or one of the RAID0 drives then there may be no real loss. Of course, if the source data drive would happen to die coincidentally with the backup drive, who’s going to be full of regret or maybe lose their job?
Personally, I wish RAID0 (striping) would not even be considered RAID. RAID isREDUNDANT Array of Independent Disks. There is NOTHING REDUNDANT about RAID0. RAID0 is strictly for speed.
If you want speed and redundancy, that would be RAID 0 + 1 or RAID10.
Simply put, if the data is worth storing, it is worth storing in such a way that you can sustain a hard drive failure without losing data. Even if you have a backup of that data, even if that backup is current, do you really want the hassle of restoring & rebuilding?
RAID1, or mirroring, uses 2 hard drives. If one fails, the other keeps on going and your NAS device stays online. Hopefully you have the network storage device configured to email you when one of the redundant hard drives fails so you can get it promptly replaced.
RAID1 is the best you can do in the case of a 2 drive NAS device.
The next step up, and probably the most common RAID is RAID5. RAID5 uses 3 or more hard drives to make your data redundant. Lose any 1 hard drive and you have no problem; lose 2, though, and you will likely sustain data loss.
For this reason, some NAS devices, like Netgear ReadyNAS, allow you to configure a “hot spare” that will automatically replace a failed hard drive. Remember, though, that for as long as it might take to “resync” the new drive, you are potentially at risk if a second drive fails.
RAID6 came in to fill this gap. With RAID6, you can actually sustain the loss of two hard drives without losing data. There is no “resync” period where you are at risk when one hard drive fails. You pay for this, though, in having to buy an extra drive up front then same as you do with a hot spare.
For most of the network storage devices we compare and review here, there are so few drives available in the device that we kind of hate to dedicate two drives to redundancy. The enterprise NAS devices with twelve hard drives would certainly be an exception.
To answer the question, “do I really need RAID NAS”, the answer is YES. Without RAID, figure that the only hard drive you have will fail, will fail at the most inopportune time, and that you will lose data when that happens.