TrueNAS ensures that different versions of different software fit together. So you update your OS, and your setup doesn’t break.
The common tasks are made easy: snapshot scheduling, snapshot replication, Samba share with a few clicks, backup to cloud, users management, one click install of applications, SMART tests, etc. Config management can be a headache.
As GP said, all these features are nice, but if you don't need them, they're just overhead.
I'm in the same boat, all I have on my NAS is Samba, zrepl (ZFS snapshots and backups) and node exporter (monitoring agent for Prometheus - handles SMART, etc). It's running Arch, and I've never had my setup "break" in more than 10 years of using this distro (though this particular NAS is not that old).
I don't care for a DB, web server and god forbid random applications doing who knows what on my NAS. But if you want your NAS to do everything, it should be great. To each their own, I guess.
Also, TrueNAS is FreeBSD which may or may not work on dinkier hardware. I'm specifically thinking of random watchdog problems on some older Realtek Gigabit NICs, where you had to use a specific patched driver which, at one point, didn't support the latest version.
Plus the setup now gets intricately coupled with the host OS. That's a big no for me. I want to treat the host OS as disposable, ephemeral and decoupled for peace of mind. The host's only job is to serve files over samba protocol and run scrub cronjobs. That's it. It gets 2 vCPUs and 24GB of ram. Stays put.
That's basically how SmartOS does it, as long as you're doing SMB or Samba. And boy, is it ephemeral: the entire OS is loaded into RAM from a USB stick (usually) on boot, and everything gets loaded from the zpool, as OC said, and if you need anything, you put it in a zone. Even VM hypervisor goes in a zone, because it's essentially free and gives you nice clean separation (and quotas, reservations, etc.).
Though NFS can only be shared from the global zone, so if you need NFS you don't get to play with zones.
> the whole thing should be marketed more like "Proxmox with batteries included".
It's not though. Even if you make all the "NAS software" part of the jails (or the half-baked Kubernetes in TrueNAS SCALE), it's not even close to Proxmox when it comes to managing VMs, containers/jails, firewall, networking, etc.
I use zfs-auto-snapshot for snapshots, it works great. I think the only thing I would want is early warning for a disk failure. I'll probably automate that. TrueNAS feels extremely heavy with too many features I don't need. There is a web server, database, etc which feels overkill for a simple home NAS IMO and having to manage the management system.
The common tasks are made easy: snapshot scheduling, snapshot replication, Samba share with a few clicks, backup to cloud, users management, one click install of applications, SMART tests, etc. Config management can be a headache.