error reported during vm migration

[Madscientist]

hi,
i am attached the screen shot of the error message i receive during a vm migration from one host to another host. after lot of struggele and investigating it is found that those VM failed to migrate where i changed the mtu=1500 value added manually to the vm config file, and do not restarted the vm like this :-

nano /etc/pve/qemu-server/.conf
Add or adjust:net0: virtio=XX:XX:XX:XX:XX:XX,bridge=vmbr0,mtu=1500

i have a mission critical proxmox cluster running with ceph, few of the vm during upgrade i can not stop or restart at this time, as upgrade to version 9 require to change the mtu value, so i edited the config file to add those mtu=1500 in the vm config. at present the cluster is running version 8.4.x , i did not migrated to version 9.1x after this error, request you to guide if there any way to change these mtu witout restarting the VM at this time , or a work around to solve this problem, request you to kindly guide.

Note:- those vm which are restarted with new mtu value is migrating without any error.

 

[fiona]

Hi,
manually editing the configuration means that the currently running state of the virtual machine does not match its configuration anymore. It's fully expected that this can lead to such issues. Never edit the configuration manually, always use the qm set command or the web UI!

 

[Madscientist]

hi
thanks for the reply , if i use qm set command , will it require a restart of the vm ?
if i use web ui, then restart of the vm is required to take the effect. i can migrate the vm without restarting the same ?
what if i migrate the host to version 9 without changing the mtu, will it break the system or vm in operation (vm which require to be active during upgrade)?