My Proxmox cluster uses nfs storage. Sometimes nfs server fails and VM remounts disks as readonly.
Trying to avoid this by adding werror=stop,rerror=stop to vm.conf like this:
ide0: nfs:101/vm-101-disk-1.qcow2,format=qcow2,rerror=stop,werror=stop,size=10G
After this when nfs fails, it tryes to...