Increase from 300 G to 400 G using the same storage, but leverage LVM on GPT inside the VM.
Host:
lvextend -L +100G /dev/mapper/guests--lolguest virsh qemu-monitor-command lolguest info block --hmp virsh qemu-monitor-command lolguest block_resize drive-virtio-disk0 400G --hmp
VM:
sgdisk -e /dev/vda gdisk /dev/vda # <-- create partition 5 partprobe /dev/vda pvcreate /dev/vda5 vgextend ubuntu-vg /dev/vda5 lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv
Always watch out for paths, partition numbers and names!
