On Thu, Jan 27, 2011 at 7:16 AM, James Hogarth <james.hogarth at gmail.com> wrote: > As per the Redhat Virtualisation Expo yesterday... API/ABI > compatibility is maintained within the point releases. If your stuff > is certified on 5.4 it will run on 5.5/5.6. > > In addition there are compatibility libraries to get anything running > on 5.X on 6.0... and when you move to 6.0 then anything running on 6.0 > will run on 6.X. This... is theory. In practice, major architectural changes will break things and need to be tested. For example, the anaconda environment for RHEL 6 does not contain the "dirname" command. The environment for RHEL 5 did. I anticipate that CentOS 6 will also lack it. Who would know that without testing their kickstart scripts? And don't get me started on the NetworkManager related changes in /etc/sysconfig/network-scripts: the new "NM_CONTROLLED" option can cause enormous confusion.