I am using the trial 7.2.2 and I am trying to migrate from OMV to Unraid. My HDDs configure in OMV was 4 drives in ZFSZ1, 1 SSD in EXT4, and 2 HDDs in mdadm raid mirror.

I installed the unassign plugin on Unraid, but I still could not mount the EXT4 drives. And I am not sure how to mount my ZFS pool without losing data. I understand that Unraid doesn't support mdadm, but can I run a VM that can use the raid and pass the drive to the VM? If so how do I achieve that?

To mount zfs, you'd have to go in terminal and force import the first time

6 minutes ago, ndowens said:

To mount zfs, you'd have to go in terminal and force import the first time

That should not be needed; typically you only need to add the zfs drives to a new pool, leave the filesystem in auto, and start the array to import the pool.

19 minutes ago, hyv said:

but I still could not mount the EXT4 drives

These may not work. There was a previous user from OVMF where they failed to mount due to having the quotas feature flag enabled, which is currently not supported by Unraid, but would need to see the diagnostics to confirm.

Does assigning the drives to the pool reformat them? I need the data in the ZFS pool. I don't have much on the EXT 4, but I would prefer this not to be a one-way journey since I am still undecided and trialling the software.

I backed up everything on all my drives, but I don't want to change any file system in case I decide to stick with OMV.

1 hour ago, hyv said:

Does assigning the drives to the pool reformat them?

Nope, to import an existing pool with Unraid, you can do this:

on main, create a new pool with the name you want and the correct number of slots (if the pool has any subpools, like special, log, cache, dedup vdevs, they must all be assigned together as part of the main pool; Unraid will sort the devices during import).

assign the pool device(s), leave the filesystem set to auto

start the array to import the pool

If the pool is not imported for some reason, it also won't be touched/damaged, and if that happens, post the diagnostics to see why it failed.

I have another question before I try to mount my drives. Is it possible to run something that can use my raid HDDs in a VM with minimal resources (like one core, 4 GB RAM) in Unraid and use them there? They are storage backups anyway; I don't need them to interact with the containers or other stuff I might install. And can I use Unraid without a drive array and only pools? So I store data, VM, and containers in the pool.

7 hours ago, hyv said:

And can I use Unraid without a drive array and only pools?

Nope, you need at least one assigned device to the array or a pool.

7 minutes ago, JorgeB said:

Nope, you need at least one assigned device to the array or a pool.

You CAN have just pool(s) - the array is now optional. Your answer implies otherwise as that was the OP question although it does actually say this (just not very clearly).