You'd have to look up what might suit your needs. I have only seen a couple of companies that offer a live state. You would either need to use kvm/qcow type tools that use virtual support or install some software that would act on the virtual hard drive just as if it were a stand alone computer.
This is one of them but you'd need lvm. http://www.storix.com/
It may be that you would have to re-create the systems and use lvm or btrfs or zfs. Otherwise the tools for kvm/qemu would have to do.
The only other way is to use some rsync sort of deal. This nas box also may have some features that could be used. Some of the advanced nas boxes have all sorts of options.