[Tinned_Tuna]

I've seen this happen to a friend. Back in the noughties they built a home NAS similar to the one in the article, using fewer (smaller) drives. It was in RAID5 configuration. It lasted until one drive died and a second followed it during the rebuild. Granted, it wasn't using ZFS, there was no regular scrubbing, 00s drive failure rates were probably different, and they didn't power it down when not using it. The point is the correlated failure, not the precise cause.

Usual disclaimers, n=1, rando on the internet, etc.

[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.