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AW: [Xen-users] Live migration and drbd

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Subject: AW: [Xen-users] Live migration and drbd
From: "Rustedt, Florian" <Florian.Rustedt@xxxxxxxxxxx>
Date: Mon, 10 Nov 2008 10:07:48 +0100
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Thread-topic: [Xen-users] Live migration and drbd
No no,

that's not right!!
You definetly need an network-filesystem for drbd primary/primary!
There are TWO systems, that access files for writing and both are not running 
the same kernel ergo doesn't "know", that the other side is actually 
locking/writing a file!

So you need OCFS & co. For doing the file-locking....

Regards, Florian

-----Ursprüngliche Nachricht-----
Von: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] Im Auftrag von Daniel Asplund
Gesendet: Montag, 10. November 2008 09:46
An: Rainer Sokoll
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Betreff: Re: [Xen-users] Live migration and drbd

> Hi,
> I have a machine running several DomU's, PVM's als well as HVM's. Each 
> DomU resides in its own LV.
> Also, I managed drbd to replicate the LV's to a second machine. Now, I 
> want to try out Xen's ability to live migrate a running DomU, that 
> means, from machine1's LV to machine2's LV. If I understood this 
> correct, during the process of migration, both LV's need to be writable.
> In a default installation, drbd only supports one primary node, but I 
> need primary/primary, correct?
> Here it comes to a cluster filesystem like OCFS - and I am stuck. How 
> can OCFS help me? Or am I totally wrong and what I want is impossible?
> The main goal, of course, is to have a redundant fail over solution.
> If my question is more related to drbd-users, I'll switch over to the 
> other list.
> Thanks,
> Rainer

Hi Rainer,

Basically the only prerequisite is that you run DRBD8, which gives you 
primary/primary, to get live migration working. You don't have to bother with 
cluster aware FS. Both nodes will not have exclusive access at the same time so 
running ext3 is perfectly fine.

You can have a look at this guide to get some additional information:

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