Hello all,

I have some questions about ZFS Expansion. Not specific to unraid, although I want to do this on my unraid server and figured people here would be knowledgeable about this sort of stuff.

 

I see that a way to add disks to existing zfs vdevs was added to OpenZFS back at the end of 2023. First think I've got to figure out is if the zfs I have on my unraid is updated enough to have that feature. I'm running ZFS Master to get ZFS support. I've had my NAS running for a while and quite honestly fell behind on updates because for one "if it aint broke don't fix it" lol, but also because I actually ran into a problem on another unraid box I was running after an update to 6.12 and I've just never gotten around to upgrading my main NAS since then cause I didn't want to run into the same issue lol (I know it has long since been fixed and there was a work around even then, I've just been slack).

 

The next and more important question is just along the lines of have people been successfully using the zpool expansion? I've got 40 TB of data on my NAS and while I do have backups (a full backup of everything and 2 more offsite backups of critical data), I'd really rather not hose the system if I can avoid it. But I'm getting low on free space with 5x 16TB drives in RaidZ2 config, and only have 3 available slots to expand. So I can't do the old method of adding another vdev of equal size to make sure the data is balanced properly. I also don't really want to just add another raidz1 3 disk array because I want to keep my 2 disk parity.

 

Also, for those that have experience or knowledge of this expansion, how fast is it usually? Can you use the array while it's expanding?

Can you add more than one disk at a time?

 

And one last question not specifically about the zfs expansion, is there any requirement to run standard (non zfs array) in unraid? When I built this nas I had a few extra 8 TB drives so I threw those in the other 3 slots and just used Unraids built in array with a single disk parity on those instead of zfs. I think I remember the reason being something to do with unraid not being able to use the zfs array for things like appdata storage and such? But I really can't remember for sure. I don't really use those drives otherwise though, I have it configured right now to use them for data ingesting and that is about it. But it's really not necessary for me to do that, so I'd be hoping I can give up that array for the full 3 slots, but if it came down to it I can leave one 8TB in there and at least get a bit more with just 2 more 16tb drives.

 

In the past I've just built a new NAS with higher storage capacity when I got low on space lol, but I don't really want to spend that much money right now. So hoping I can do something to just expand the zfs array.

 

Thanks in advance for any help / advice on the subject.

 

This should answer most of your question, but any doubts, please ask:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/4/#findComment-1537164