====== ZFS over iSCSI ======

  * IT IS: This storage type let to use remote ZFS system using iSCSI.
  * IT IS NOT: ZFS over iSCSI block device

Proxmox need access using SSH to target iSCSI device (i.e. Zyxel NAS326).

It is trying to execute following command:
<code bash>
/usr/bin/ssh -o 'BatchMode=yes' -i /etc/pve/priv/zfs/192.168.28.150_id_rsa root@192.168.28.150 zfs list -o name,volsize,origin,type,refquota -t volume,filesystem -Hr
</code>

To give access to target SSH, create new SSH access key and authorize it on target machine:
<code bash>
# run on Proxmox node:
mkdir /etc/pve/priv/zfs
ssh-keygen -f /etc/pve/priv/zfs/192.168.28.150_id_rsa
ssh-copy-id -i /etc/pve/priv/zfs/192.168.28.150_id_rsa.pub root@192.168.28.150

# login once to target from each proxmox node, to accept key:
ssh -i /etc/pve/priv/zfs/192.168.28.150_id_rsa root@192.168.28.150
</code>