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RE: [Xen-users] Convert CentOS system to Xen image?

To: "Igor Chubin" <igor@xxxxxxx>
Subject: RE: [Xen-users] Convert CentOS system to Xen image?
From: "Ross S. W. Walker" <rwalker@xxxxxxxxxxxxx>
Date: Wed, 2 Apr 2008 09:52:57 -0400
Cc: James Pifer <jep@xxxxxxxxxxxxxxxx>, Xen List <xen-users@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-users] Convert CentOS system to Xen image?
Igor Chubin wrote:
> On Mi, Apr 02, 2008 at 09:19:19 -0400, Ross S. W. Walker wrote:
> > James Pifer wrote:
> > > Attempted to do this using netcat + ssh and here's my next problem. The
> > > CentOS server is using LVM, so instead of getting an img file of around
> > > 8 gig that I expected, I got one that is 18 gig, or the size of the LV.
> > >
> > > I tried it anyway and I get a valid boot sector not found.
> > >
> > > Any suggestions?
> >
> > Don't do netcat, create a fresh PV with the same installed packages
> > as on the old machine and copy the configuration of the old server
> > that is pertinent. You could look at creating a kickstart file to
> > have those packages installed during the initial install, or just
> > install base/core and add in by hand the missing packages via yum.
> You can use dd or cat (+ netcat | ssh)
> and it will copy raw image,

Yes, but that makes a lot of assumptions about the source and
destination systems that might not be true, like, the source
system is physical and the destination virtual, so the
destination will have different disk names, the source may
have software RAID1, but the destination being virtual may
already be backed by RAID1 and not need it. The source disk
may be infinitely bigger then the allocated destination
(ie source drive 250GB, root partition is 16GB LV and only
3GB of it is used, but netcat'ing will try to transfer full
250GB into a 16 or 32GB guest volume).

> but creating LVM and filesystems on its logical volumes
> has several advantages:
> 1. You can filesystems with any layout and sizes
> 2. You transfer only data and not "freespace" as in case of
> dd/netcat usage
> Disatvantage:
> 1. You should create LVM and FS first.

I don't think I grasp your advantages/disadvantages points
here, maybe it's a language barrier where the subtleties
were lost in translation.

I do agree that LVM is the way to go, as it's pros far
outweigh it's cons.

> >
> > For data partitions like /home you can do a dump, sftp, and restore.
> Also you can use rsync
> (it should be installed on both hosts).

rsync will indiscriminately copy-over files that it shouldn't.

No this is why companies sell stand-alone P2V products.

You can look for these, but if you had just created the PV and
duplicated the important configuration it'd be up and running
and in testing phase now.


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