Proxmox/Shrink LVM-Thin

Shrink to make Backup Volume

lvcreate -V 1T --thin -n backup pve/data && \
mkdir -p /mnt/backup && \
mkfs.ext4 /dev/pve/backup

cat <<EOF > /etc/systemd/system/mnt-backup.mount
[Unit]
Description=Thin-volume for Proxmox-Backup

[Mount]
What=/dev/pve/backup
Where=/mnt/backup
Type=ext4
Options=defaults

[Install]
WantedBy=multi-user.target
EOF

systemctl enable mnt-backup.mount && \
systemctl start mnt-backup.mount

Ref: https://forum.proxmox.com/threads/shrinking-of-lvm-thin-possible-best-workaround.71217/