[NV+ v2] 4 disks, 2 separate RAID-1 volumes?

StephenB wrote:
... Using RAID-1 doesn't eliminate the need for a backup, though it would provide another way to recover data. That could be worth the extra overhead, especially if the data is critical.

PapaBear wrote:
But not if the two volumes are different data as the member plans.

Of course it does.

If any disk in two volume set fails, you can recover the data from the other disk in the pair using off line tools on any system with a single SATA port. Basically the overhead gives you two independent copies of your data on the NAS. If you have a 4 disk RAID-5 system, you need at least 3 SATA ports on the recovery system, and the recovery is technically much more difficult.

So yes, the volume pair idea is less efficient. But if you want to be able to recover data from the original disks, it is much more practical to do that with RAID-1. I know a few IT folks who stick with RAID-1 exclusively for that reason.