Proxmox only grows disks. The restore dialog gets an optional "Root
disk GiB" field for container backups; with a size, the backup is
restored as a new guest with --rootfs <storage>:<N> (Proxmox's advanced
restore mode).
- A smaller disk is only allowed for a new VMID, checked in the dialog
and again in cli.restore(): with force, Proxmox deletes the old disks
before it unpacks, and a failed unpack then removes the guest.
- The size must be a positive integer (0 gives an unlimited subvol on
ZFS/dir storage) and above the used root disk space of a running
guest.
- The confirm screen is a separate DANGER screen with a red border: it
says mount points are dropped and their backed-up files land in the
root disk, raw lxc.* lines can come back under root@pam, root disk
options are not carried over, and the used space is no fit check.
- Never --unique or ignore-unpack-errors.
Design: docs/plans/lxc-shrink.md (section A).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
