Xen users - Dec 2008 - Using DRBD w/Xen disk images under CentOS?

Hi All,

One other question.  I have a bunch of VM''s using Xen disk images under
the dom0''s filesystem.  Is it possible to use DRBD to
"mirror" the Xen
disk images for Xen VM''s to use on another box for live migration, etc?

-- 
Daniel Kao
Übermind, Inc.
Seattle, WA, U.S.A.



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On Tue, Dec 02, 2008 at 04:57:10PM -0800, Daniel Kao wrote:
> One other question.  I have a bunch of VM''s using Xen disk images
under the
> dom0''s filesystem.  Is it possible to use DRBD to
"mirror" the Xen disk
> images for Xen VM''s to use on another box for live migration, etc?
No. DRBD replicates block devices, as the name suggests. If you want
DRBD, use the flexibilty (and speed, compared to a file-based backend)
of LVM.

Rainer

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On Tue, 2 Dec 2008, Daniel Kao wrote:
> Hi All,
>
> One other question.  I have a bunch of VM''s using Xen disk images
under the
> dom0''s filesystem.  Is it possible to use DRBD to
"mirror" the Xen disk
> images for Xen VM''s to use on another box for live migration, etc?
If your talking about having two xen boxes with DRBD under them and being 
able to live migrate between them yes, we do this today in production in 
two clusters.

><>
Nathan Stratton                                CTO, BlinkMind, Inc.
nathan at robotics.net                         nathan at blinkmind.com
http://www.robotics.net                        http://www.blinkmind.com

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Nathan Stratton <nathan@robotics.net> writes:
> On Tue, 2 Dec 2008, Daniel Kao wrote:
>
>> Hi All,
>>
>> One other question.  I have a bunch of VM''s using Xen disk
images
>> under the dom0''s filesystem.  Is it possible to use DRBD to
"mirror"
>> the Xen disk images for Xen VM''s to use on another box for
live
>> migration, etc?
>
> If your talking about having two xen boxes with DRBD under them and
> being able to live migrate between them yes, we do this today in
> production in two clusters.
Do you use drbd primary/primary and live migration? If it works, which
version of drbd and which kernel/xen version are you using? What is in
domUs?

I have tons of problems with this setup: jittery domU clock, random
domU crashes (luckily no dom0), network going down randomly in domU
after migration, etc, but have no clue what could be the problem lvm,
drbd or xen, or all three.

-- 
To sto si frustriran, zavidan tko zna na cemu i sto ne vidis dalje od
svoje guzice je tuzno. Da onda barem imas toliko samokontrole da
sutis umjesto da pravis budalu od sebe... izgleda da si prestar da se
promjenis na bolje. - Davor Pasaric, hr.comp.mac


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I''m using Centos 5.2 with Xen 3.30 and DRBD 8.2.6. Occasional issues
with live migration but otherwise it all works nicely. I use
Primary/Secondary migration, dual primary not allowed in DRBD config.

Rob

-----Original Message-----
From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Aleksandar
Ivanisevic
Sent: 04 December 2008 16:11
To: xen-users@lists.xensource.com
Subject: [Xen-users] Re: Using DRBD w/Xen disk images under CentOS?

Nathan Stratton <nathan@robotics.net> writes:
> On Tue, 2 Dec 2008, Daniel Kao wrote:
>
>> Hi All,
>>
>> One other question.  I have a bunch of VM''s using Xen disk
images
>> under the dom0''s filesystem.  Is it possible to use DRBD to
"mirror"
>> the Xen disk images for Xen VM''s to use on another box for
live
>> migration, etc?
>
> If your talking about having two xen boxes with DRBD under them and
> being able to live migrate between them yes, we do this today in
> production in two clusters.
Do you use drbd primary/primary and live migration? If it works, which
version of drbd and which kernel/xen version are you using? What is in
domUs?

I have tons of problems with this setup: jittery domU clock, random
domU crashes (luckily no dom0), network going down randomly in domU
after migration, etc, but have no clue what could be the problem lvm,
drbd or xen, or all three.

-- 
To sto si frustriran, zavidan tko zna na cemu i sto ne vidis dalje od
svoje guzice je tuzno. Da onda barem imas toliko samokontrole da
sutis umjesto da pravis budalu od sebe... izgleda da si prestar da se
promjenis na bolje. - Davor Pasaric, hr.comp.mac


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"Robert Dunkley" <Robert@saq.co.uk> writes:

> I''m using Centos 5.2 with Xen 3.30 and DRBD 8.2.6. Occasional
issues
> with live migration but otherwise it all works nicely. I use
> Primary/Secondary migration, dual primary not allowed in DRBD
> config.
What version are you using? Compiled from the source or rpms from
somewhere?

[...]



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