[libvirt] non trivial question

Hi all. I have very special task - i have some vps on kvm, that sometimes needs external support help (administration). But i can't trust external workers and need to known what files are changed. As i understand best of all - create backup before work and after. After that check it for difference and decide apply this work or not. Vps need to run all time. (no downtime for work). How can i do that and what tools i need to use? Is that possible? Thanks for all answers. -- Vasiliy Tolstov, e-mail: v.tolstov(a)selfip.ru jabber: vase(a)selfip.ru