[layer8]

This is the reason why I would always use RAID 6. A second drive failing during rebuild is significantly likely.

[SlightlyLeftPad]

You’re far better off having two raids, one as a daily backup of progressive snapshots that only turns on occasionally to backup and is off the rest of the time.

[layer8]

I don’t understand how it is better to have an occasional (= significantly time-delayed) backup. You’ll lose all changes since the last backup. And you’re doubling the cost, compared to just one extra hard drive for RAID 6.

Really important stuff is already being backed up to a second location anyway.

[nine_k]

Fine for on-site backup, but my NAS is mostly for media storage.

Also, many drives are not happy to restart too many times.