[CentOS] Virtualization platform choice

[Kenni Lund]

Den 29/03/2011 15.41 skrev "David Sommerseth" <dazo at users.sourceforge.net>:
> This makes me wondering how well it would go to migrate from SL6 to CentOS
> 6, if all KVM guests are on dedicated/separate LVM volumes and that you
> take a backup of /etc/libvirt.  So when CentOS6 is released, scratch SL6
> and install CentOS6, put back the SL6 libvirt configs ... would there be
> any issues in such an approach?

I would not expect any issues at all, I would expect it to "just
work". As long as you use CentOS6+/SL6+ (or Fedora 12+) *with* the
libvirtd/virsh/virt-manager management tools, you shouldn't run into
any major problems. This is because RH has implemented a stable guest
ABI and stable guest PCI addresses, so the virtual hardware will
remain the same on different KVM/libvirt hosts.

> And what about other KVM based host OSes?

That depends on a lot of things...in general, if you're not using one
of the RH-based distributions mentioned above, use the latest version
of the distribution in question, to hopefully receive some of the
upstreamed bits from the RH-distributions. Luckily things are slowly
stabilizing, so it should only be a question of time, before any
distribution with a recent kernel, recent qemu-kvm executable and a
recent libvirt version, should be compatible with each other in terms
of moving KVM-guests around.

The main problem is Windows guests, which easily chokes on hardware
changes (forced reactivation of Windows or unbootable with BSOD). Each
qemu-kvm version will behave differently, so moving from one major
qemu-kvm version to another (0.1x -> 0.1y), will most likely change
the virtual hardware seen by the guest, unless you have libvirt etc.
configured to keep track of the guest hardware.

If it's only Linux guests, it should work fine when moving the guests
between any recent Linux distribution with KVM. Of course, if you
don't use libvirt or a similar management solution, the hardware in
the guest will likely change, for example causing your MAC-addresses
of your NICs to change, etc, when moving to a new KVM host.

Best regards
Kenni