RAID-Z1: increase amount of disks

[guyman]

Hi,

for a bigger Project (SIEM), we want to start with 3 NVMe, using Raid-Z1.
Later, I want to have the chance, to increase the pool, using 4 instead of 3 disks of same model/manufacturer.
Is it possible to just increase the pool without any problems to re-setup something?

If I understood it in a right way, currently, this is not possible, but maybe will with ZFS 2.3?

https://github.com/openzfs/zfs/pull/15022
https://github.com/gamanakis/zfs/commit/93e443b85ffc1209c3c16e1e0022c7da905c1251

It was discussed in some older threads here.
Maybe, the proxmox-staff has some ideas to that?

Thanks
Ronny

 

[waltar]

You understood it in a right way, currently, this is not possible, but maybe will with ZFS 2.3 !
But then you will have inbalance so writes are slower and even reads until balance is reached.
For just 1 nvme it makes more sense to integrate this now as it's not that much more expensive to a new server
as you will have the cons later. You even could recopy everything after an extension but that comes with a downtime also
and so that makes all less sense at all for the price of just 1 nvme.

 

[leesteken]

Please be aware that running VMs on RAIDz1 might be disappointing in both speed (IOPS) and usable space (when compared to hardware RAID5 with BBU, as discussed before on this forum).

 

[waltar]

I don't think so with nvme as even a single nvme has enough oom on iops. That's the case when using raidz with hdd's.

 

[guyman]

You understood it in a right way, currently, this is not possible, but maybe will with ZFS 2.3 !
But then you will have inbalance so writes are slower and even reads until balance is reached.
For just 1 nvme it makes more sense to integrate this now as it's not that much more expensive to a new server
as you will have the cons later. You even could recopy everything after an extension but that comes with a downtime also
and so that makes all less sense at all for the price of just 1 nvme.

Well ;-), we do not use just simple drives, but only enterprise classified. Means, a 7.68 TB NVMe on 3 or 5 systems, matters. A bunch of 3 is around then ~ 3000 Euro. Scaling and deploying a new product, it is not always easy to calculate storage needs and upcoming requirements on a regulated market. That´s way we thought about using ZFS, starting with 3 disks, and increasing storage size, if we really need it.

 

[waltar]

Yes, that's right, it was just to know the pros and cons of your planning as even the code isn't look that stable to be released yet. The decision is still on your side and nobody want to take it from yourside. I thought you just have 1 system and not 3 or more which makes quiet a difference with enterprise nvme's. Good luck to your project.