Ubuntu Upgrade to KVM Server

Hi,

Firstly I am not an Ubuntu expert and therfore not a KVM wiz either.


I have inherited a standalone physical server that is running Ubuntu 16.10 (EOL) that runs KVM with a few Virtual machines runnin on it. I need to upgrade Ubuntu to 18.04.01 LTS and I am wondering what is the best way to do this upgrade and migrate the VMs.


Note: I have 1 of these KVM servers at each DC and will need to upgrade both eventually. The hardware is compatible with Ubuntu 18.04LTS


The images and backups of the VMs are on NFS mounts contained on centralised storage arrays.


Has anyone done this lately. If you have a plan that you followed I would appreciate if you could share it with me.


My question are:
If i shutdown the VMs, dismount the NFS shares and then do a clean install of Ubuntu 18.04LTS will I be able to use the old VMs/images in the new version of Ubuntu/KVM? I realise i will need to setup the network configs and local user accounts again.


Or is it better to follow the upgrade path (16.10 --> 16.04 --> 17.10 --> 18.04) in order to re-use the VMs again.


Any help would be much appreciated. Thanks in advance.