[Solved] Fastest way to upgrade two raid5

This is not an answer to your question, just an observation.

In the situation you're in I would think twice. It is possible that in the future mdadm will be deprecated in the OMV GUI in favor of BTRFS. So if you still want a Raid5, since it's still unstable on BTRFS, it might be interesting at this point for you to switch to for example RaidZ2 ZFS with those 7 disks.

Quote from ceres2018

From what i read so far i need to start with empty disks right?

Yeah.

Quote from ceres2018

Is there any possibility to do this inplace without restoring from backup?

I have 7 SATA ports, which could make it tricky.

So would it be possible to start with, for instance, 3 disks RaidZ2 ZFS (copy everything from 4disk raid5, then copy the 3disk raid5) and than later on extend that RaidZ2 to 7 disks?

It's not possible. You would need another PC where you can mount your current Raid5 temporarily until you have copied the data.

Or a pcie to sata card with 4 ports, but make sure your power supply will support that many simultaneous drives.

If you have a backup it would be the cleanest, create the Raid and restore from the backup.

Quote from chente

It is possible that in the future mdadm will be deprecated in the OMV GUI

I have seen there are two open issues in GH to carve out mdadm into a plugin (like already done with FTP). But I think this does not mean mdadm will not be supported by OMV anymore.

Quote from macom

I have seen there are two open issues in GH to carve out mdadm into a plugin (like already done with FTP). But I think this does not mean mdadm will not be supported by OMV anymore.

Compatible will always be managing it from CLI. As for the GUI, I don't know what will happen. I have read that it will probably be removed from central OMV, that remains to be seen. It could become a complement but that also remains to be seen.

In any case, I think that mdadm's days are numbered. ZFS and BTRFS surpass it in many ways. Over time it is logical to think that mdadm will disappear, although it may still take a few years for that.

In a case like the OP's, with 7 disks ready to raid, I personally would never use mdadm. But each one makes the decisions that seem most appropriate for their case.

Quote from BlueCoffee

why do you think mdadm will be gone?

I think it will disappear because it is an old technology. ZFS and BTRFS surpass it in many ways. There are other file systems in development as well.

Actually the same Raid5 problem that BTRFS has, so does mdadm, but it's never talked about. People have assumed it for many years.

The best option currently to do a Raid5 is ZFS in my opinion.

Quote from BlueCoffee

Is ZFS okay on OMV? i know nothing about it. Ive always used mdadm.

The ZFS problem in OMV is the incompatibility between ZFS and debian licenses. If that problem didn't exist I'm pretty sure ZFS would be fully integrated into the core OMV GUI.

You currently have an openmediavault-zfs plugin that allows you to manage this file system. But depending on what you want to do, you may at some point need to do it from the CLI. It is a useful plugin, but not complete.

In any case, once the Raid is configured in ZFS you can completely stop worrying, it is rare that you have to do something in it.

The licensing problem also means that to use ZFS with debian you have to compile ZFS into the kernel every time there is an update, etc. It is all done automatically but carries certain risks. The solution to avoid that is to install a proxmox kernel (ubuntu), problem solved. Ubuntu doesn't care about licensing issues, apparently. If OMV was based on ubuntu instead of debian we wouldn't have this problem