[pve-devel] [RFC qemu-server 22/22] command line: switch to blockdev starting with machine version 10.0

[Fiona Ebner]

Am 16.06.25 um 12:40 schrieb DERUMIER, Alexandre via pve-devel:
>>> +	# QEMU recursively auto-removes the file children, i.e. file
>>> and format node below the top
> 
> From my tests, it's not removing backing nodes when snapshots are used,
> at least when then are defined with nodename. Don't have tested with
> autogenerated backing nodes, I'll verify with linked qcow2 clones.

Yes, the comment explicitly mentions 'file' children, not 'backing'. But
actually, implicit backing children (i.e. for linked clones) seem to
also be removed just fine:

> [I] root at pve8a1 ~# cat /etc/pve/qemu-server/600.conf | grep disk-0.qcow2
> scsi1: nfs:109/base-109-disk-0.qcow2/600/vm-600-disk-0.qcow2,iothread=1,size=1G
> [I] root at pve8a1 ~# echo '{"execute": "qmp_capabilities"}{"execute": "query-named-block-nodes"}' | socat - /var/run/qemu-server/600.qmp | jq | grep disk-0.qcow2 | wc -l
> 18
> [I] root at pve8a1 ~# qm set 600 --delete scsi1
> update VM 600: -delete scsi1
> [I] root at pve8a1 ~# echo '{"execute": "qmp_capabilities"}{"execute": "query-named-block-nodes"}' | socat - /var/run/qemu-server/600.qmp | jq | grep disk-0.qcow2 | wc -l
> 0

If you need further functionality for the external snapshot support, you
can add it later :)