Chris Hoff’s BlackHat presentation titled “The Four Horsemen of the Virtualization Apocalypse” was described here by Ellen Messmer to Chris’ dislike. Her spin may have been slightly too negative, but in any case she reports interesting points, among them Chris’ comment that it just won’t work if you VMotion a virtual firewall (VFW). While Chris is right in general, moving a VFW will in fact work in some simple corner cases, basically when both locations are indistinguishable in networking terms (same subnet, same VLANs, no NAT on the VFW itself etc.). So you can VMotion a firewall, but just a little bit … if you are not so lucky all hell breaks lose.
What’s more worrying is that all the same problems will happen if you VMotion any VM in presence of any firewall (virtual or physical): either you VMotion between two locations that are identical in terms of routing, VLANs etc. or you are in trouble. Any relative motion between firewall and VM will create the same troubles.
The really revealing bit about Chris’ comment is that most VMware deployments are still so simple that all VMotion happens in the simple corner cases. So don’t get too close to your firewall when you do VMotion.
ps. I have, of course, my own agenda here.