At the moment I have my NAS setup as a Proxmox VM with a hardware RAID card handling 6 2TB disks. My VMs are running on NVMEs with the NAS VM handling the data storage with the RAIDed volume passed through to the VM direct in Proxmox. I am running it as a large ext4 partition. Mostly photos, personal docs and a few films. Only I really use it. My desktop and laptop mount it over NFS. I have restic backups running weekly to two external HDDs. It all works pretty well and has for years.
I am now getting ZFS curious. I know I’ll need to IT flash the HBA, or get another. I’m guessing it’s best to create the zpool in Proxmox and pass that through to the NAS VM? Or would it be better to pass the individual disks through to the VM and manage the zpool from there?
There is no way to get acceptable IOPS out of HDDs within Proxmox. Your IO delay will be insane. You could at best stripe a ton of HDDs but even then one enterprise grade SSD will smoke it as far as performance goes. Post screenshots of your current Proxmox HDD/SSD disk setup with your ZFS pool, services, and IO delay and then we can talk. The difference that enterprise gives you is night and day.