This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-users] Re: Having Windows XP HVM on qcow diskfile and snapshots

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Re: Having Windows XP HVM on qcow diskfile and snapshots.
From: Geert Janssens <info@xxxxxxxxxxxx>
Date: Thu, 21 May 2009 17:58:35 +0200
Cc: Arun Sharma <arunain@xxxxxxxxx>, Javier Guerra <javier@xxxxxxxxxxx>
Delivery-date: Thu, 21 May 2009 08:59:38 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <90eb1dc70905210844i7a20a0a5l372f23836fccc096@xxxxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
Organization: Kobalt W.I.T.
References: <5ce3e56d0905210726m79f5adc8n4bbc0efc18b4d78f@xxxxxxxxxxxxxx> <200905211732.13460.info@xxxxxxxxxxxx> <90eb1dc70905210844i7a20a0a5l372f23836fccc096@xxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: KMail/1.11.2 (Linux/; KDE/4.2.2; i686; ; )
On Thursday 21 May 2009, Javier Guerra wrote:
> On Thu, May 21, 2009 at 10:32 AM, Geert Janssens <info@xxxxxxxxxxxx> wrote:
> > * The Guest machines are all configured to get their IP address via dhcp,
> > and each guest config has it's own unique MAC address. So each guest will
> > appear on their own ip address
> > * There is no data on the guest disk images (only OS and applications).
> > All variable data is accessible via samba shares. So I don't delete
> > anything valuable by overwriting a disk image with the new master.
> if there's no state on those images, you can mount them as readonly
> and use the same for all DomUs.  of course, any update means shutting
> down
I never tried this... Won't Windows complain if it's running off of a read 
only disk ? I suppose Windows is writing to temporary files, or is keeping 
state in it's registry. I'm not interested in these local state differences 
between guests, that's why I can simply replace one guest's disk with an 
updated master copy. But I just don't know if Windows can handle a readonly 
"C" drive.
As for shutting down, that's no problem. I can plan for maintenance downtime 
pretty easily. The guests aren't used fulltime.

> > It works ok, but I'm using a lot of wasted diskspace. I still intend to
> > try and setup an LVM based disk image and use LVM snapshots for each
> > guest. This would give me essentially the same thing but with less wasted
> > diskspace. The experiment will have to wait until I find some time for it
> > though.
> note that using snapshots and a 'master' (either LVM or qcow) means
> you can't change the 'master' and expect the snapshots to catch the
> updates
I'm well aware of that and I can live without this advanced feature. As I 
understand it from reading this list, ZFS is currently the only filesystem 
that has something along those lines. But I may even misunderstand that much.

Kobalt W.I.T.
Web & Information Technology
Brusselsesteenweg 152
1850 Grimbergen

Tel  : +32 479 339 655
Email: info@xxxxxxxxxxxx

Xen-users mailing list