qm-rescan
Rescan all storages and update disk sizes and unused disk images of a virtual machine.
TLDR
Rescan all storages and update disk sizes and unused disk images of a specific virtual machine
$ qm rescan [vm_id]
Perform a dry-run of rescan on a specific virtual machine and do not write any changes to configurations
$ qm rescan --dryrun [true] [vm_id]