Expand Raid 5 with two drives on Quts

[Krs89]

Hi, I have a TS-h973AX running Quts with three HDD drives in Raid 5. I want to add two more drives to expand my storage capacity, but that would convert my Raid to striping (Raid 0 if I'm correct) Will I be able to switch back to Raid 5 or 6 once the new empty drives are added? Is this expansion only possible if I switch to QTS?

[diwiwi]

Answer is NO
https://www.qnap.com/en/how-to/faq/arti ... o-like-qts

You can only add a RAID group.

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[dolbyman]

This is all over the place ..why would adding drives turn anything to RAID0?

You cannot add drives to ZFS vdevs (yet) .. But even if you could ..it would not turn RAID5(1 parity) to RAID0 (no parity)

On md RAID you can add drives to RAID5 or RAID6 but..not without killing the whole system first (to switch from QuTS to QTS)

[Kunzite]

Maybe he's talking about adding single drive vdevs (rather than a mirror) to the pool?
Not sure QuTS allows you to add a mirror vdev (or a single disk vdev) to a RAIDZ pool, and anyway AFAIK that isn't recommended (instead, the vdevs ("RAID Groups") from a pool should be balanced.

I see no other reasonable option than to start from scratch. Going QTS won't help either, because it also means starting from scratch - can't migrate the disks between QTS and QuTS.
(until Matt Ahrens finishes the OpenZFS RAIDZ Expansion feature... which seems to be on hold unfortunately. Then we'd have to see that included in QuTS Hero).

[Krs89]

I see, so the only way to solve my mistake would be to move all data to another storage unit, and start from scratch by adding the new drives, right? Luckily I still have my old NAS and drives with enough capacity to store my files temporarily

[dolbyman]

Well, there is new developments

QuTS 5.1 will (presumably) add the feature to add drives to an existing ZFS pool. (QNAP has a webinar upcoming to announce)
http://www.qnap.com/static/en/webinar/webinar.html

But having a full backup at all times (and not just plan for it when it's too late, because then it's too late) is a good idea nonthless

[Kunzite]

I'm afraid it won't - the RAIDZ expansion branch isn't merged yet in OpenZFS master.
I'd be glad to be wrong though.

[dolbyman]

Well, official QNAP support said this feature is included in the next major version

https://www.reddit.com/r/qnap/comments/ ... &context=3

[Kunzite]

Interesting, but we'll see. AFAIK RAIDZ migration is not supported to ZFS, so at least that part is doubtful (with all due respect to QNAPDaniel).
We might get single->mirror migration. Sorry, I prefer to be pessimistic and pleasantly surprised

[Kunzite]

And I'm glad to report that I was wrong. The beta was announced, and... "Users can now expand a storage pool by adding disks to expand an existing RAID group within the pool. When expanding the RAID group, you can also migrate the RAID group to a different RAID type."
How on Earth did they do that? Especially the migration? I'm tempted to kill my storage pool, just to test this.

[Kunzite]

By the way, you cannot migrate from mirror/single to parity. Given what (little) I know about ZFS, this is a very understandable limitation.
And, when migrating the RAIDZ level, you need an extra drive - that means one more than you'd think (e.g. 2 drives to migrate from RAIDZ to RAIDZ2).
https://www.qnap.com/en-us/operating-sy ... hero/5.1.0

This isn't Matt Ahrens' RAIDZ expansion feature (or, it might be a heavily modified/expanded version); and I don't think we'll see RAIDZ level migration on TrueNAS or Linux anytime soon. QNAP did something more ambitious.