SELinux and dedicated disks

Hi all, one of my "lingering issues" since I am back working in Linuxland (especially CentOS): I have the "habit" to have dedicated virtual disks (or similar) for data, e.g. /var/lib/mysql (so I can snapshot them separately, clone and move between VMs etc.) But that makes SELinux unhappy. I was surprised, actually.. What do I have to add to the SELinux contexts to allow this to happen? Regards Peter