2. Snapshots

Source: TrueNas Replication Task

Note! Running another Truenas on bare metal also allows you to run proxmox pbs as a container! If you have just as me one production device and a small backup server with like 4cpus and 16gb of ram then this would be great solution for you. Otherwise you need to have at least 3 devices. 

This method involves backing up your Truenas datasets to another Truenas VM running on another host. This could for instance be your backup PVE instance on which you also run Proxmox backup server as a VM. 

• Now, it is up to you if you want to use dedicated drives for this (which is best) however you can also attach virtual disks such you can use one disk for Truenas dataset backups and for PBS backups. This is what I am currently running in my home lab at least.  

Truenas VM with virtual drives

If you want to go the virtual drive route then there is one little tweak that you need  to make for TrueNas VM to recognize different drives. 

1. Go your backup PVE's shell and nano into /etc/pve/qemu-server/VM-ID.conf
2. In here you want to add serial numbers to the disks that you added to the VM
3. This does not need to be complicated, they just need to be different for each drive. For instance you could use serial=DRIVE00X for each drive and changing X for each added drive. For instance with two drives it looks like this 

scsi0: local-zfs:vm-1002-disk-0,discard=on,iothread=1,size=12G,ssd=1,serial=DISK001
scsi1: tank:vm-1002-disk-1,discard=on,iothread=1,size=2000G,ssd=1,serial=DISK002