[CentOS] CentOS upgrade in Xen domU?

Mike Edwards pf-centos at mirkwood.net
Sun Oct 21 18:42:35 UTC 2007

I'm running into a slight problem trying to upgrade a CentOS 4.4
install to 5.0.

The configuration:
CentOS 4.4 is an old install that used to boot natively.  That has
since been backed up and restored to two seperate LVs (as the original
install had two partitions).  The host system now runs Debian, and I've
been able to successfully boot the old CentOS 4.4 install under Xen
(with a Debian domU kernel, but that's besides the point).

I've decided to upgrade the CentOS domU to CentOS 5.  After determining
that the recommended upgrade path is to do so via the installer, I
grabbed the CentOS installer kernel/ramdisk and configured my domU to
boot from those.  The installer comes up without a problem.

Things get hairy when the installer takes a look at the 'disks'.  I
receive the following message:
/dev/xvda currently has a loop partition layout.  To use this disk for
the installation of CentOS, it must be re-initialized, causing the loss
of ALL DATA on this drive.

It looks like the installer doesn't like the fact that there are no
partitions (which is correct, as the 'disk' is actually a logical
volume under lvm).  As I'm trying to do an upgrade, and not blow away
my existing setup, this isn't going to work.

My question, therefore, is - how do I tell the CentOS 5 installer to
ignore the fact that there are no partitions, and to simply do the
install?  As mentioned previously, the CentOS domU does boot perfectly
fine, and given the prevalence of volume groups, logical volumes and
virtual machines these days, it seems rather silly to have an installer
absolutely rely on the existence of partitions before it'll let one do
an upgrade or install.

Mike Edwards                    |   If this email address disappears,   
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"Our progress as a nation can be no swifter than our progress in education.
The human mind is our fundamental resource."
  -- John F. Kennedy

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