Proxmox – Shrink local ZFS disk
1- boot gparted and shrink partitions leaving free space as you like
2- in pve shell
$zfs set volsize=<new size>G rpool/data/vm-<vm id>-disk-<disk number>
Ex: zfs set volsize=50G rpool/data/vm-141-disk-0
3- edit vm config in /etc/pve/qemu-server/vm-id.conf
virtio0: local-zfs:vm-<vm id>-disk-<disk number>,size=<new size>G
IF can not boot and corrupted partition table for shrinked disk:
boot gparted
gdisk /dev/sda
press
v
x
e
w
y
Done!