On the Proxmox host? If so, just use the Proxmox installer for this. IIRC, you have the choice of a ZFS mirror (which would be my preference) or standard Linux software RAID1. See: https://pve.proxmox.com/wiki/Installation
More than I have time or space to list, but here are a few big ones:
Everything has checksums (data and metadata), so ZFS knows if your data’s been corrupted. If it has a place to get a clean copy, it will repair any corruption. If it doesn’t, at least it can definitively tell you there’s a problem.
Snapshots are baked into ZFS, they’re near-instant and near-free (they take a tiny amount of metadata, other than that, the only additional space they take is the delta in the data). The standard .qcow2 disk image files do support shapshots, but it’s a much slower operation.
Data compression is enabled automatically.
If you have a ZFS system for backups (like maybe a FreeNAS/TrueNAS server), you can do them use ZFS replication for rapid and frequent backups using PVE-zsync (PVE-zsync - Proxmox VE)
Online pool expansion is trivial–if you need more storage, whack in another pair of disks and run something like zpool add rpool mirror disk1 disk2. The disks are formatted, brought online, and the pool is expanded, all in one step.
ZFS supports mirrors of arbitrary width–if you need more redundancy, you can set up a 3-way, 4-way, etc. mirror. Write performance would obviously suffer, though.
I suggest to setup a Raid10 (this is also suggested from proxmox staff…) with 4 - 8 HDDs or better SSDs (ext4 FS).
And for the Backups I use PBS (Proxmox Backup Server) with a RAID-Z variant (ZFS Raid). For offsite backups also PBS via OpenVPN connection from HQ to branch…
fun because proxmox do not recommend to use zfs over an hardware raid
Do not use ZFS on top of a hardware RAID controller which has its own cache management. ZFS needs to communicate directly with the disks. An HBA adapter or something like an LSI controller flashed in “IT” mode is more appropriate.
I must admit a still keep away from ZFS pool, still use LVM and software raid (yes I can be old school)