Proxmox LVM-thin over iSCSI without a native storage plugin

Proxmox still doesn’t ship a native LVM-thin over iSCSI storage plugin, so you have to wire it up yourself. It’s not hard, just a few extra steps on the TrueNAS side and some LVM commands on Proxmox.

Why bother?

LVM-thin gives you snapshots and thin provisioning, and iSCSI lets you put that storage on a separate box. The combo is great for a homelab SAN. The official docs cover iSCSI and LVM-thin separately, but nobody shows the full path.

Set up the iSCSI target on TrueNAS

First, create a zvol on TrueNAS. Make it big enough for your VMs. Then create an iSCSI target and extent, and associate them. Note the target IQN and the portal IP.

Connect Proxmox to the target

Install open-iscsi on the Proxmox host:

apt install open-iscsi

Discover the target:

iscsiadm -m discovery -t st -p 192.168.1.100

Log in:

iscsiadm -m node --login

Now you should see a new disk, like /dev/sdb. Create a physical volume and a volume group:

pvcreate /dev/sdb
vgcreate vg-iscsi /dev/sdb

Then create a thin pool:

lvcreate -L 100G -T vg-iscsi/thinpool

Add the storage to Proxmox

In the Proxmox web UI, go to Datacenter → Storage → Add → LVM-Thin. Select the volume group vg-iscsi and the thin pool thinpool. Give it a name like iscsi-thin. That’s it — you can now create VMs and containers on it, with snapshots working.

Watch out

Make sure the iSCSI target is available before Proxmox tries to mount it at boot, or you’ll get timeouts. Also, this isn’t a clustered filesystem — don’t put the same LUN on multiple Proxmox nodes unless you really know what you’re doing. For a single-node homelab, it’s fine.

If you want to compare performance, check out my Proxmox VE ZFS Benchmark with NVMe post. And if you’re doing this in a cluster, the Clustered iSCSI as LVM on LVM-Thin SAN guide covers the multi-node setup.

If you’d rather pay for this

TrueNAS offers a paid version with support, but the free version does everything you need here. I wouldn’t pay just for this feature. The only real reason to pay is if you want enterprise support or a turnkey SAN appliance. For a homelab, the manual setup is fine.