ZFS special device with raidz2 dont work

[petruzzo]

Hi to all
I try to add a special device to my raidz2 pool but I have an error when I try.
The command I use is zpool add Backup special raidz2 /dev/sdc /dev/sdd /dev/sde /dev/sdf and this is the result

root@pbs1-d2600:~# zpool add Backup special raidz2 /dev/sdc /dev/sdd /dev/sde /dev/sdf
invalid vdev specification: unsupported 'special' device: raidz

Spoiler: proxmox-backup-manager versions --verbose

proxmox-backup 3.3.0 running kernel: 6.8.12-4-pve
proxmox-backup-server 3.3.0-2 running version: 3.3.0
proxmox-kernel-helper 8.1.0
proxmox-kernel-6.8 6.8.12-4
proxmox-kernel-6.8.12-4-pve-signed 6.8.12-4
proxmox-kernel-6.8.12-2-pve-signed 6.8.12-2
proxmox-kernel-6.8.8-3-pve-signed 6.8.8-3
proxmox-kernel-6.8.8-2-pve-signed 6.8.8-2
proxmox-kernel-6.5.13-6-pve-signed 6.5.13-6
proxmox-kernel-6.5 6.5.13-6
proxmox-kernel-6.5.13-5-pve-signed 6.5.13-5
proxmox-kernel-6.5.11-7-pve-signed 6.5.11-7
proxmox-kernel-6.5.11-6-pve-signed 6.5.11-6
ifupdown2 3.2.0-1+pmx11
libjs-extjs 7.0.0-5
proxmox-backup-docs 3.3.0-1
proxmox-backup-client 3.3.0-1
proxmox-mail-forward 0.3.1
proxmox-mini-journalreader 1.4.0
proxmox-offline-mirror-helper 0.6.7
proxmox-widget-toolkit 4.3.3
pve-xtermjs 5.3.0-3
smartmontools 7.3-pve1
zfsutils-linux 2.2.6-pve1

Package versions

any idea because this happens

 

[UdoB]

Just use a triple(!) mirror!

You should create a vdev with the same redundancy level, not with the same topology.

(And a RaidZ2-vdev would be slower while the "maximize size" aspect is irrelevant.)