[Openstack-operators] Live Migration and instances stores

Dave Spano dspano at optogenics.com
Tue Nov 27 20:22:52 UTC 2012

Not sure if this is sufficient for you or not, but I currently use the rbd portion of ceph for Openstack. I don't currently do live migrations because it's not feasible for me to setup the extra storage. Instead, I do block migrations, and these work rather well. 

The only bad part is that you have to release the floating ip, migrate the instance, and then reassign it to the vm. Otherwise, the vm's networking gets messed up. I use nova-network in multi-host mode, so I'm not sure if the same behavior would happen with Quantum. 

Sébastian Han wrote a great article on block migration if you're interested. 


I noted at the bottom of the article that the block migration functionality won't take affect with currently running instances. You have to terminate, then re-spawn them after you make your changes to nova.conf. 

Dave Spano 

----- Original Message -----

From: "Jonathan Abdiel Gonzalez Valdebenito" <jonathan.abdiel at gmail.com> 
To: openstack-operators at lists.openstack.org 
Sent: Tuesday, November 27, 2012 11:38:24 AM 
Subject: [Openstack-operators] Live Migration and instances stores 

Hi all, 

First at all I'm glad to write to the list :D thanks for reading! 

I'm currently experimenting with lot of ideas to store the instances(/var/lib/nova/instances) and do a live migration with them, well here it's a tiny resume: 

DRBD + OCFS2: Works pretty well but as it depends on DRBD which it's a raid 1 system it can't grow any further than the initial size... bad idea if you want some scalability 

GlusterFS: A bit slow, it can take some minutes to replicate but works, the only problem that it has it's that you can't perform a live migration, the reason, cache != none or that's what the logs says 

Ceph: It runs pretty good tests, but it's slow with the machines in my lab, and throw some errors about being too slow. Anyway, I tried the live migration and it didn't work either. 

Now I'm currently starting my test with MooseFS but don't know yet if it will work, according to the openstack manual it's a good idea, but I will like to have the experience of the list on this matter, does anyone try any of this options or another successfully? or have other options that I haven't found yet? 

Thanks in advance for all you answer! 


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