SUSE Linux Enterprise servers (SLES) need subscription licenses to receive updates (and technical support by SUSE staff, if running on a “standard” or “priority” subscription), and you have the choice of one-year or three-year licenses. Those licenses come in the form of “activation codes” that are used to register each server with the SUSE registration service, still known as NCC (“Novell Customer Center”).
SLES-equipped servers can run Xen, a hypervisor shipped for free with each SLES version, and you can run as many SLES virtual machines on top of that hypervisor as you like (license-wise), as long as the physical machine is a properly licensed SLES server. (There are other options for licensing, if you’d rather employ a different hypervisor, but that’s outside the scope of this article.)
A nice feature is that you need not provide activation codes with these virtual machines (VMs), so once you’ve set up the base system (“Dom0”), you’re ready to go. But how does that work, what does that mean for typical (and not so typical) scenarios, and what can you do if things don’t work as expected? Continue reading