Raid: Add or remove disk

[Aurex126]

Good morning,

I wanted to tell you the following question or guide me how to do it:

When you have a RAID (RAID5, RAID6, RAID10,...). Can disks be added and/or removed from that RAID?

If so, how could it be done?

I am on version 8.2.2

Thank you so much!

 

[UdoB]

Some people here could fill a complete cloud with the answer as it is to unspecific.

What kind of "Raid" do you have in mind? Hardware? Software? ZFS? Btrfs?

Assuming ZFS and aiming for a very short answer: YES, disks can be added. But SOMETIMES you need to follow "surprising" rules to do so. (Topology, vdev-extension not fully implemented yet, RaidZ top-level vdev can not get removed, ... )

Details are relevant!

Does this help? No? Give us more details, and... have fun!

 

[Aurex126]

Hello!First of all, thank you very much for the quick response.The RAID is software, and SFZ.I show you capture.Thank you!

 

[UdoB]

The RAID is software, and SFZ.I show you capture.

Fine!

The recommended way to add more disks is to add the same type of vdev. In your case that would mean to add two mirrored devices.

Unfortunately I have never done this via the Web Gui. Someone else would need to chime in here.

Caution: this is your "rpool", so probably you are booting from it. This means adding news disk should be done in a specific way to keep the bootability of all disks. This again is not trivial as it requires some work to prepare some partitions.

You an find all necessary information here: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#chapter_zfs

While "Changing a failed bootable device" (in that chapter) contains all necessary information I must admit that there are some pitfalls and some experience on that level would really help - and might be necessary. Also this is CLI-only, not Gui.

I have no step-by-step guide for you, sorry.

It seems you start with a difficult task ;-)

 

[Kingneutron]

> Can disks be added and/or removed from that RAID?

( It transpires that the "RAID" is a ZFS rpool mirror )

We need more details about what your intentions are here. What are you trying to accomplish?

Are you running low on disk space, want to move both disks in the mirror to larger disks?

Add more disks to make the mirror a "raid10 equivalent"?

Are you wanting to downgrade and only have 1 drive in the mirror? You can do that - but there is a safe way and an unsafe way. The UNsafe way renders the extra disk unusable/unbootable.

It's not recommended to expand a ZFS boot mirror into a "raid10 equivalent" for $REASONS. You would be better off making a separate pool from 2x new disks to separate your OS and data and mitigate the risk of a disk (or multiple disks) dying.

https://github.com/kneutron/ansitest/tree/master/proxmox

I have scripts to migrate a ZFS boot/root mirror pool to either smaller or larger disks.

 

[alexskysilk]

When you have a RAID (RAID5, RAID6, RAID10,...). Can disks be added and/or removed from that RAID?

removed- no. added- depends on the controller. HP SSA controllers allow this; LSI does too.

If you mean MDRAID- cant do either AFAIK.

ZFS- vdevs can be added. they can be removed (CAREFULLY) on a striped mirror. a "vdev" is equivalent to a RAID subrank, and can either be a disk or a stripeset.

If so, how could it be done?

If this is an actual consideration for deployment, "RAID" is probably not what you want. have a look at unraid (https://unraid.net/.) If you're technically inclined, a snapraid based solution is also workable.