ZFS features missing in JBOD/Span?

[Dunuin]

Hi,

I'm using a 4x 8TB raidz1 pool in my NAS and want to backup it. I thought it might be a good idea to just buy 3x 8TB for the backup pool to save some money but I've read that a JBOD/span doesn't have the full ZFS features in comparison to the zraid.

What are those differences except that all data of the backup is corrupted if a single drive of the backup pool fails?

 

[sretalla]

I'm not sure where you're hearing that... a ZFS pool is just that.

Redundancy and performance is up to the pool layout/VDEV structure, but nothing else is "missing" from a striped pool (pool of 1 VDEV in stripe).

Without redundant data, ZFS can detect corrupt files during a scrub, but will not have a good copy to correct the problem with. (you can set the pool to keep multiple copies of files even in the same VDEV, but that will cost you the space of that number of copies, so would question why you would do that).

 

[JaimieV]

Setting up the backup array to a stripeset with no redundancy is how I always used to do it. There's a minor risk - if your backup loses a disk, it's gone of course; during the purchase and rebuild phase (four+ days in my case!) your primary is at risk if *that* fails enough to lose data.

It's a low risk of dual failure.I was happy with doing that at home, but I'd never do it in a corporate situation.

Currently my backup is on RAIDZ1 (see Show: blocks below), because I now have a backup NAS with enough disk slots.