Re: [Xen-users] pushing updates across lv-based domU clones

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Tue, May 19, 2009 at 2:03 PM, Pallab Chakrabarty
<pchakrabarty@xxxxxxxxxxxxxxx> wrote:
> The main LVM is :/dev/xen_vg/cent_os and the clone created:
> /dev/xen_vg/clone1

> And also incase the baseVM(xen_vg/cent_os) is updated (suppose a new
> software loaded & require distribution seamlessly to all such cloned domUs),
> the same should be reflected on the cloned domUs..

You can't. That not how LVM clone works.
Unless you ABSOLUTELY know what you're doing, I suggest you stay away
from LVM clone. They can save some space (depending on how you use
it), but with extra performance penalty and the possibility of losing
your data (when the snapshot is full).

If you want to be able to update on one place and all changes
automatically goes to ALL domUs, then there are no supported method
(at least on RHEL anyway) for doing so. You have to update all domU
one by one. The easiest workaround is to have nfs-mounted /usr ro, but
it may or may not work depending on how you use it.

The only OS/virtualization method I know which supports updating on
one place only is zones/containers on (open)solaris.

If your goal is to save space, IMHO the best way is to use
iscsi-mounted volume from a storage server that supports snapshot and
clone (e.g. Netapp, opensolaris, etc.)

-- 
Fajar

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