[CentOS-virt] xen+drbd Question

Tue Aug 26 14:02:20 UTC 2008
Aleksandar Ivanisevic <aleksandar.ivanisevic at 2e-systems.com>


after i've read this post


I've given up on xen and drbd disks for now, and am using phy:, but 
you'll have to give it drbd device not the volume

disk = [ "phy:/dev/drbd14,xvda,w" ]

Unfortunately, that means that you'll have to handle setting drbd 
devices primary/secondary yourself. I've written a wrapper script around 
drbdadm+xm and it has been working more or less ok.

That also means no live migration since drbd device needs to change 
state sometime mid-migration, but save/move/restore has been working ok 
for me with really minimal downtimes.

There is also a primary/primary setup with newer drbd but it was awfully 
unstable when i was testing it a few moths ago, most of the time it was 
crashing and taking down the complete cluster with it.


Alexandre Biancalana wrote:
> Hi list,
>  I installed two new servers to be our virtualization HA. This servers
> have CentOS 5.2, Xen 3.0.3, Drbd 8.2.6. The setup is ok, lvm drbd
> resources sincronizing, Guest VM running without any problem.
> My only doubt is that I can only use drbd resources inside guest vms
> when I specify the disk resource in vms config like this:
> disk   = ['phy:/dev/VolGroup00/vappprtem01,hda,w' ]
> if I specify de disk like:
> disk   = [drbd:vappprtem01,hda,w' ]
> The Guest VM found the disk but this appear with zero size.
> As far what I read the second way is the correct to live migration
> work without any race condiction...
> This link say that centos has a problem with block-drbd script
> provided by drbd, is anybody aware of that ?
> http://lists.xensource.com/archives/html/xen-users/2008-08/msg00176.html
> Any hints ?
> Best Regards,
> _______________________________________________
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> CentOS-virt at centos.org
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Aleksandar Ivanisevic
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