[CentOS] CentOS upgrade in Xen domU?

Mike Edwards pf-centos at mirkwood.net
Mon Oct 22 12:45:02 UTC 2007

Thank you for the reply, Alain.

Since CentOS doesn't have a recommended on-line upgrade path (why?!), I
figured I'd go with the recommended path of using the installer.  To
that end, I was wondering if I was missing something (boot option,
perhaps?) that would tell anaconda to bypass the partition check, and
just get on with the install.

I eventually gave up after several hours of frustration, and followed
a HowTo on the CentOS site written by someone upgrading from the 4.4
server install to 5.0.

I still repeat my earlier question - why should a modern installer,
with the existence (and popularity!) of LVM and Xen, refuse to operate
on disks when it cannot find a partition table?  It seems upstream is
severely limiting their install options in this case.

Thank you again.

On Mon, Oct 22, 2007 at 01:37:14PM +0200, Alain Spineux babbled thus:
> Hi
> The installer way is not the only one to upgrade your system!
> Especially if it fail to detect your disk/partitions.
> You should be able to to make the upgrade using "yum upgrade/update"
> Google on the web about centos upgrade for more info.
> Regards.
> On 10/21/07, Mike Edwards <pf-centos at mirkwood.net> wrote:
> > 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.
> -- 
> Alain Spineux
> aspineux gmail com
> May the sources be with you

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