Proxmox ZFS vs LVM-Thin: Which Storage Should You Choose?
The installer asks once and it's hard to change later. What each one actually gives you.
By Brandon Sheley · Updated
Short answer: pick ZFS if you have two or more disks, plan to cluster with replication, or want your data checksummed; pick LVM-thin (the installer default) for a single-disk standalone node, hardware RAID, or very little RAM. ZFS's RAM use is capped by default on new installs, so that's no longer the deciding factor it was.
Claims below about ZFS behavior on Proxmox are from Proxmox's own ZFS documentation.
ZFS vs LVM-Thin at a Glance
| ZFS | LVM-thin | |
|---|---|---|
| Installer default? | No, pick it under Options when choosing the disk | Yes (ext4 or XFS install creates a thin pool called local-lvm) |
| Snapshots | Yes | Yes |
| Thin provisioning | Yes | Yes |
| Checksums / detects bit rot | Yes, and repairs it when the pool has redundancy | No |
| Compression | Yes (lz4 recommended) | No |
| Software RAID across disks | Built in: mirror, RAIDZ1/2/3 | No (needs mdadm or hardware RAID underneath) |
| Proxmox storage replication | Yes, required for it | No |
| RAM use | Uses RAM as read cache (ARC); capped by default on new installs | Minimal |
| On hardware RAID | Don't: ZFS needs direct disk access | Fine |
When ZFS Is the Better Choice
- You have two or more disks for guests. A ZFS mirror gives you redundancy and self-healing reads without any extra layer.
- You want a cluster with replication or HA on local disks. Proxmox storage replication only works with ZFS, and it's the usual way to get HA on mini PCs (see building a mini PC cluster).
- You care about knowing your data is intact. ZFS checksums every block; LVM-thin and ext4 will happily return corrupted data without telling you.
- You want compression for free. lz4 costs very little CPU and often saves real space on VM disks.
The RAM question is mostly solved now. Since Proxmox VE 8.1, the installer limits ZFS's cache (ARC) to 10% of the host's memory, capped at 16GiB, on new installs. Older installs used ZFS's own default of up to half or more of RAM and need the limit set by hand in /etc/modprobe.d/zfs.conf. Proxmox's rough rule is 2GiB plus 1GiB per TiB of storage.
When LVM-Thin Is the Better Choice
- One disk, and you want simple. On a single NVMe drive in a mini PC with no cluster, ZFS's main advantages (redundancy, replication) don't apply, and LVM-thin is fast and light.
- A hardware RAID controller. Proxmox's docs say not to put ZFS on a RAID controller with its own cache. Use LVM-thin on the RAID volume, or flash the controller to IT mode and let ZFS have the disks.
- Very little RAM. On an 8GB node, LVM-thin leaves all of it for guests.
- Cheap consumer SSDs. ZFS writes more for the same workload than ext4 on LVM, so low-endurance QLC drives wear faster under it. If you use ZFS on consumer SSDs, check the drive's rated TBW and keep an eye on its wear level.
One LVM-thin trap: thin provisioning lets you hand out more disk than you have. If the thin pool actually fills, guests start getting write errors. Watch the pool's usage, not just each VM's.
How to Choose at Install Time
The choice is made in the Proxmox installer: on the disk selection screen, click Options and pick ext4 or XFS (which gives you LVM-thin for guests) or one of the ZFS layouts (RAID0 for one disk, RAID1 for a mirror, RAIDZ for three or more).
Changing the boot disk's layout later means reinstalling. You can still add ZFS pools or LVM-thin pools on other disks at any time, so a common setup is the OS on one small drive and guest storage on a second drive or a mirrored pair formatted however you choose.
What I'd pick: ZFS for anything with two disks or that will join a cluster, LVM-thin for a single-disk standalone node or anything on hardware RAID. If you're unsure and have the RAM, ZFS is the one you're less likely to wish you'd chosen later.
Related Resources
Mini PC Proxmox Cluster
Why ZFS replication is the usual storage choice for small clusters.
TrueNAS Scale on Proxmox
Why you shouldn't put TrueNAS's pool on a ZFS-backed virtual disk.
Proxmox Backup Server Setup
Snapshots aren't backups. Where the backups go.
Hard Drive & SSD Price Tracker
Live $/TB on NVMe, SATA SSDs and hard drives.
LXC vs VM on Proxmox
The storage and backup gotchas that differ between the two.
Best Mini PC for Proxmox
How many NVMe slots each kind of mini PC gives you.
Frequently Asked Questions
Should I use ZFS or LVM-thin on Proxmox?
Use ZFS if you have two or more disks for guests, want replication or HA in a cluster, or want checksums that catch corrupted data. Use LVM-thin for a single-disk standalone node, a hardware RAID controller, or a host with very little RAM. LVM-thin is the installer's default; ZFS is under Options on the disk screen.
How much RAM does ZFS use on Proxmox?
On installs since Proxmox VE 8.1, the installer caps ZFS's ARC cache at 10% of host memory, up to 16GiB. Older installs may let ZFS use half or more of RAM unless you set zfs_arc_max in /etc/modprobe.d/zfs.conf. Proxmox's rough guide is 2GiB plus 1GiB per TiB of storage.
Can I switch from LVM-thin to ZFS later?
Not for the boot disk without reinstalling. You can add a ZFS pool on other disks at any time and move VM disks to it with Move Storage, which is a common way to get there without a rebuild.
Can I use ZFS with a hardware RAID card?
Proxmox's documentation says not to run ZFS on a hardware RAID controller that has its own cache management, because ZFS needs direct access to the disks. Use an HBA or a controller flashed to IT mode for ZFS, or use LVM-thin on top of the RAID volume.