Comments on: Live Migration and Synchronous Replicated Storage With Xen, DRBD and LVM

By: Keith

Keith — Mon, 14 Mar 2011 17:21:13 +0000

The shift from Secondary to Primary is handled by the xen drbd block script. In the VM config we specify to use this on the disk line.

“disk = [ 'drbd:vm_shaolin,hda1,w' ];”

You’re right though, without the xen block script, the block device would remain as a secondary and writing to it would not work without manual intervention.

By: paul

paul — Wed, 02 Mar 2011 13:04:18 +0000

I’m confused on how this can work. The DRBD docs say that in a Primary/Secondary resource, the secondary side can be neither read from nor written to. Is there a DRBD mode change going on that’s not explictly in your article?

http://www.drbd.org/users-guide-emb/ch-admin.html#s-roles

By: keith

keith — Sat, 13 Nov 2010 05:34:14 +0000

Stuart, I think you would still run into that bug if you were using a storage method other than DRBD, right? I don’t usually use the xen version supplied with EL5, its just too old! I do try to run their kernels (especially in domU), but if you need to patch the dom0 kernel until the fix makes its way into the redhat kernels I would go for it!

By: Stuart Gathman

Stuart Gathman — Sat, 13 Nov 2010 05:11:08 +0000

I know it’s asking a lot, but this doesn’t work on Centos5.5 migrating from a 32-bit dom0 to a 64-bit dom0 or vice versa. The save image is copied to the target, the drbd primary is switched, but the xen restore chokes on the save image from the other arch. This has been fixed at xensource, but the patch hasn’t percolated to EL5 yet. We can still quickly switch using drbd by shutting down and rebooting on the other machine, but the live migration would have been cool.

By: Line

Line — Tue, 11 May 2010 12:20:19 +0000

Conhe?a

By: keith

keith — Fri, 30 Apr 2010 18:14:53 +0000

Sure

By: Ab Circle Pro Review

Ab Circle Pro Review — Fri, 30 Apr 2010 15:21:23 +0000

Good day website owner might I make use of a number of of the data from this post if I provide a link back again for a internet site?

By: Zachery Dunny

Zachery Dunny — Mon, 19 Apr 2010 11:43:22 +0000

Would be really interesting to see your traffic spike if you had any stats enabled

By: Jon

Jon — Tue, 13 Apr 2010 14:27:15 +0000

This is awesome! I’m deploying a xen environment within the next few weeks, and I’ve been looking for a replication solution. Not only did I find what I was looking for, but I get live migration too! Woohoo!