Usually if you are doing something like that you are passing a SATA controller card/HBA directly to the VM and the drives are connected through that.

So all of the data would still be on those drives even if you blew up that VM entirely or proxmox corrupted itself.

On some levels it would be easier to recover from a system failure because you could have VM backups or snapshots to rely on.

It's a more advanced setup but it's not inherently "bad" or more risky. And yes, usually people are doing that type of thing because they don't need an entire separate physical server if they already have one with some spare cores and ram.

For example I have truenas running on a server that has a 6700k and 16GB of ram. That's overkill CPU for a Nas and I already have a 32 core 128GB ram server running. I'm migrating truenas to that server and giving it 4 cores and 32GB (still overkill for my needs). That will let me shut that other server down and save on my electric bill.

More exciting are the people that host Their firewall/router like OPNSense/PFSense as a VM on their system! 😄

My NAS is a FreeBSD virtual machine. The drives are passed through directly to the Virtual Machine, so it is possible to take the drives out, and attach them to another virtual machine or bare metal computer running FreeBSD or TrueNAS and read them.

I honestly, think it's pretty bad practice.

Hey, I got this big fancy server-

Let me install Vmware/Proxmox on it, and create some VMs.

I want a fancy dashboard to click and install my apps. and I need storage. Let me put a TrueNAS/Unraid VM on my proxmox.

Oh right, I need storage for another VM. Let me connect Vmware/Proxymox to TrueNAS/Unraid via ISCSI/NFS.

Oh this is the pinnacle of technology /s.

(Rather, then just using the hypervisor built into unraid/truenas....)

Or, my favorite, is installing a full-blown storage OS, just because you need a windows file share....

I don't miss the TrueNAS community, and all of the stupid crap coming from it.

Just because it can be done it doesn't mean that is a good idea to do it. It all depends on what is your are trying to do and your risk profile. For me Networking, storage and computing are all in different devices.

I virtualize my NAS because it's small (only several TB) and therefore it can be backed up like any other VM with PBS or dumped as a qcow image. A full restoration is extremely easy because I can simply have another node pull the backup from PBS. Also I can migrate the entire NAS to another node so it stays up when I have downtime.

It mostly depends on your comfort level. Generally it is frowned on. I have a proxmox cluster with two dedicated machines. One for truenas and one for unRAID.

They both get basically the entire resources from the physical servers and have dedicated hbas. I haven't run into any performance issues, and actually prefer running it this way because if the nas vm dies for some reason I can still log into the hypervisor to fix it.

That said, I don't think I'd ever use virtual disks in a nas and I also wouldnt run vms off of the storage in the nas vm. At least not for the same cluster. I also make sure to have backups in case anything bad does happen

On my proxmox, I make a mergefs filesystem that I just mount to my lxc containers that need shared storage.

Hard to guess at for any given situation, but a few pluses that come to mind depending on the drive arrangement would be taking out any network latency issues between a client and the nas. Or if you have a VM using the nas as its operational drive it takes out the 'oops, lost the link and my OS drive went away' mid run factor. Keep all your container/vm traffic internal and have that single VM sync back to a bare metal... Might have to consider some ideas on that front myself now that I think of it.