Zfs can become painfully slow if you don’t have RAM for it. I tried to run ZFS on my old setup with 64GB RAM and with moderate amount of virtual hosts and it was nearly useless with heavier io-loads. I didn’t try to tweak settings for it, so there might be some workarounds to make it work better, I just repartitioned all the storage drives with mdadm raid5 array and lvm-thin on top of that. Zfs will work with limited memory in a sense that you don’t risk losing data because of it, but as mentioned, performance might drop significantly. Now that I have a system which has memory to run raidz2 it’s pretty damn good, but with limited hardware I would not recommend it.
LVM itself is pretty trivial to move on a another system, most modern kernels just autodetect volume groups and you can use them as any normal filesystem. If you move full, intact, mdadm array to a new system (and have necessary utils installed) it should be autodetected too, but specially with degraded array manual reassembly might be needed. I don’t know what kind of issues you’ve been getting, but in general moving both lvm and mdadm drives between systems is pretty painless. Instead of mdadm you could also run lvm-mirroring on the drives so it’ll drop one layer off from your setup and it potentially makes rebuilding the array a bit simpler on another system, but neither approach should prevent moving drives to another host.
Lvm-thin is more flexible and while it might be a slightly slower on some scenarios I’d still recommend using that. Maybe the biggest benefit you’ll get from it is an option to take snapshots from VMs. Mounting plain directories will work too, but if your storage is only used by proxmox I don’t see any point in that over LVM setup.
Zfs can become painfully slow if you don’t have RAM for it. I tried to run ZFS on my old setup with 64GB RAM and with moderate amount of virtual hosts and it was nearly useless with heavier io-loads. I didn’t try to tweak settings for it, so there might be some workarounds to make it work better, I just repartitioned all the storage drives with mdadm raid5 array and lvm-thin on top of that. Zfs will work with limited memory in a sense that you don’t risk losing data because of it, but as mentioned, performance might drop significantly. Now that I have a system which has memory to run raidz2 it’s pretty damn good, but with limited hardware I would not recommend it.
LVM itself is pretty trivial to move on a another system, most modern kernels just autodetect volume groups and you can use them as any normal filesystem. If you move full, intact, mdadm array to a new system (and have necessary utils installed) it should be autodetected too, but specially with degraded array manual reassembly might be needed. I don’t know what kind of issues you’ve been getting, but in general moving both lvm and mdadm drives between systems is pretty painless. Instead of mdadm you could also run lvm-mirroring on the drives so it’ll drop one layer off from your setup and it potentially makes rebuilding the array a bit simpler on another system, but neither approach should prevent moving drives to another host.
Lvm-thin is more flexible and while it might be a slightly slower on some scenarios I’d still recommend using that. Maybe the biggest benefit you’ll get from it is an option to take snapshots from VMs. Mounting plain directories will work too, but if your storage is only used by proxmox I don’t see any point in that over LVM setup.