[SWLUG] Learning to juggle with Xen

[Justin Mitchell]

On Sat, 2006-03-04 at 10:17 +0000, Rich Williams wrote:
> What I want to know is, can I install a Xen-enabled Ubuntu, and then
> run my old system inside Xen, relatively untouched?
i dont know if ubuntu has pre-built xen packages, hopefully someone else
can answer that.  but the other part yes.

> >From what I've read, it sounds like I should be able to do this, but
> a lot of what I've read seems to concentrate on setting up new
> systems inside Xen, rather than wrapping up existing ones.

It should mostly 'just work' to run an existing system inside a xen
guest (domU), your xen config says which partitions (or loopback
filesystems) each guest is allowed access to, and which disk device name
they will appear as.

the distro you're running within a xen guest is pretty much normal
except for a few things:
1. its running on a kernel that the xen host (dom0) supplies, not the
one installed within the guest.
2. the disks it sees are virtualised, as described above.
3. the ethernet interfaces are also virtualised, but the typical setup
makes these virtual interfaces appear as bridged onto the same network
as the real ether card. 

so if this is a router setup, you could have a bit of fun getting the
networking setup right, although its also possible to allow a guest to
have direct (and sole) access to a piece of hardware like additional
ethercards.

for more typical server type applications you should be able to just
shove it xen and have it work with no changes.