I have not run all three of these in production, and this article is research rather than testing. I am labelling that at the top rather than in a footnote, because a comparison written from documentation and a comparison written from six months of use are different things and it is not always obvious which one you are reading.
What I can do usefully is separate the three by the assumption each one is built on, because that is what actually decides the choice and it is the part most comparisons skip in favour of feature tables.
The one-sentence version
Proxmox is a hypervisor that can store things. Its unit of work is a virtual machine or a container. Storage exists so those have somewhere to live.
TrueNAS is a storage system that can run things. Its unit of work is a dataset. Apps exist so the storage has something to serve.
Unraid is a media server built around a storage model nobody else uses. Its unit of work is a share on an array of mismatched drives, and its defining feature is that those drives do not have to match.
Everything below follows from those three sentences.
The storage models are genuinely different
This is the part worth understanding, because it is a structural difference rather than a preference.
ZFS, which TrueNAS is built on and Proxmox supports, stripes data across a group of drives with parity. Every drive in a group spins for a read, the group has to be the same size to be used fully, and expansion has historically meant adding a whole group rather than a single drive, though single-drive RAIDZ expansion has since arrived. In exchange you get checksums on everything and a transactional write path that avoids the write hole entirely. The capacity arithmetic is the standard parity arithmetic, which I have worked through in RAID levels explained.
Unraid’s array is not RAID. Each data drive holds a complete filesystem, and one or two dedicated parity drives cover the rest. This produces three consequences people either love or find alarming:
- Drives can be any size, as long as no data drive exceeds the parity drive. Add one drive at a time, whatever you found cheap.
- Only the drive being read has to spin, which is a real and continuous electricity saving on a large array that is mostly idle. Worth costing with the power cost calculator if your array is big.
- Lose more drives than you have parity for and you lose those drives, not the array. The rest of the filesystems are intact and readable. That is a meaningfully different failure mode from a striped pool.
The cost is write speed, since a write touches the data drive and the parity drive rather than being spread across many, which is why Unraid pairs the array with a cache drive by default.
Proxmox is agnostic and that is the point. It will use ZFS, LVM, Ceph, or a directory, because storage is a means rather than the product. If you want ZFS you get ZFS, with less of the management interface TrueNAS wraps around it.
Pick by what your machine is for
- Mostly virtual machines, storage secondary. Proxmox. It is the only one of the three whose primary object is a VM, and trying to make either of the others into a hypervisor is working against the design.
- Mostly storage, and you care about integrity. TrueNAS. Checksums, scrubs, snapshots and replication are what it is for, and its interface is built around them rather than bolted on.
- A pile of drives of different sizes, mostly media. Unraid. The mixed drive support is not a workaround, it is the design, and no amount of ZFS tuning replicates it.
- You want to add one drive at a time, cheaply, forever. Unraid, fairly decisively.
- You want one machine to do everything. All three will try. Proxmox with a storage VM, or TrueNAS with apps, are both common and both involve compromise. Be honest about which half you will be annoyed to compromise on.
The things that decide it in practice
Licensing. Proxmox and TrueNAS have free editions with paid support subscriptions available. Unraid is commercial and paid. That is a real difference in kind rather than degree, and worth checking the current terms directly since all three have changed their models over the years.
What happens when it breaks at 2am. Proxmox and TrueNAS are both built on well-documented open foundations, so a problem tends to be searchable in general terms. Unraid’s array is specific to Unraid, which makes its forum the primary resource rather than one of many. All three have active communities, which matters more than most feature comparisons acknowledge.
Migration cost, which is asymmetric. Moving from Unraid to ZFS means rebuilding the array and copying everything, because the storage models are not compatible. Moving between systems that both use ZFS is much easier, since a pool can be imported. That asymmetry is worth weighing at the start, when it costs nothing.
Power, which nobody includes. Unraid’s single-drive spin-up is a genuine running saving on a large mostly-idle array, and a ZFS pool that spins every drive on every read is genuinely more. On an eight-drive array that difference is real money over years, and it is the kind of thing that never appears in a feature table. Cost yours rather than assuming either direction.
What I am not going to tell you
Which is fastest, which is most reliable, and which handles your particular hardware. Those require running all three on the same machine for long enough to mean something, and I have not.
Two things I would do before committing, both cheap. Run whichever you are leaning toward in a virtual machine first, with fake disks, and click through the thing you will do most often. And read the migration path out of it, because that is the cost you will pay if you are wrong and it is the one nobody researches until it is too late.
FAQ
Can Proxmox replace a NAS?
It can serve files, and people do run it that way, usually with ZFS underneath or by passing the disks through to a storage virtual machine. What you give up is the storage-focused management interface that TrueNAS wraps around the same filesystem: snapshots, replication and share management are things you will configure rather than click. If storage is the point of the machine, that is friction every week rather than once.
Is Unraid’s array actually RAID?
No, and the name is a fair warning. Each data drive holds its own complete filesystem and dedicated parity drives cover the array, rather than data being striped across drives. That is why drives can be mismatched, why only the drive being read has to spin, and why losing more drives than you have parity for costs you those drives rather than everything.
Which uses the least electricity?
Unraid has a structural advantage on a large, mostly-idle array, because a read spins one drive rather than all of them. How much that is worth depends entirely on your drive count and how idle the array really is, so it is arithmetic rather than a general claim: put your own numbers into the power cost calculator. On a small array that is busy most of the time, the difference largely disappears.
Can I run local AI models on any of them?
All three run containers, so all three can run a model runtime. The constraints are memory and the absence of a graphics card, which are hardware questions rather than operating system ones, and they are the same on all three. I have worked through what that means in can you run AI on a NAS.
Should I virtualise TrueNAS under Proxmox?
It is a common setup and it works, with one condition that is not optional: pass the storage controller through to the virtual machine rather than handing it virtual disks, so ZFS is talking to real hardware. Done properly it is a reasonable way to get both. Done casually it puts a layer between ZFS and the disks it is checksumming, which undermines the reason to run ZFS at all.
Which should a first-time home server user pick?
Whichever matches the sentence at the top that describes your machine, and if none of them clearly does, start with what you will actually do most days. Storage first suggests TrueNAS, mismatched drives and media suggest Unraid, and virtual machines suggest Proxmox. Any of the three is a reasonable first choice, and the migration cost out is what you should check before committing rather than after.
Sources
- This comparison is built from each project’s own documentation and the design decisions those describe, not from running all three side by side. I have labelled it as research at the top for that reason.
- Storage model behaviour, licensing terms and feature sets all change. Check each project’s current documentation before deciding, since a comparison article ages faster than the software does.
- The parity and capacity arithmetic referenced here is the same as in RAID levels explained, computed by the code behind the NAS capacity calculator.
- No performance figure, reliability claim or power measurement for any of the three appears on this page, because I have not measured any of them.