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Re: [Xen-users] Cannot boot with LVM inside Xen DomU

On Mon, Jul 11, 2011 at 12:24 AM, Prakhar Srivastava
<prakhar.apj@xxxxxxxxx> wrote:
> Hi,
> I am going to copy the domO PV i.e. /dev/sda to a logical volume and use
> that to boot a Xen guest.

I assume you've got the basics covered already? e.g.
- what you're trying to (i.e. copy with dd) will end up WASTING lots
of disk I/O for writes, since it'll write the entire disk instead of
just used space
- your new LV must reside on another disk (i.e. NOT sda) with at least
the same of larger size
- if you use dd, it will be almost impossible to mount domUs storage
in dom0 later due to the PV having the same UUID

... and so on.

> I have been using Eucalyptus images for Xen to rum them from an LVM
> backend.
> Anyways, I am going to try and use virt-manager for installing Xen PV guests
> and hope I am able to setup LVM within.

Good luck.

Just make sure you're fully aware of the consequences. RHEL/Centos use
LVM on domU by default because it enables adding storage to domU
online (i.e. with "xm block-attach", and adding the new disk as new
domU PV). It works, but it also makes it damn hard to manage domU's
files from dom0.

Some people would prefer to simply just extend the LV, and (if domU
still uses partition) extend the partition. There's some domU downtime
involve there, but it makes it easier to manage domU's files from dom0
(for example, if you want to use LVM snapshot on dom0's side to backup
domU's files).


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