> We had to do the same downgrade with openvswitch, the newest version, under 
> heavy load, corrupts packets in-transit, but we do not have the time to 
> investigate the issue further.

Daniele, what was the openvswitch version before and after the upgrade?  And 
which ethernet drivers do you have?  The corruption maybe related to the 
drivers you have (the issues may be triggered by the way openvswitch flows are 
configured in Icehouse vs Havana).

Thanks.

From: Daniele Venzano 
<daniele.venz...@eurecom.fr<mailto:daniele.venz...@eurecom.fr>>
Organization: Eurecom
Date: Sunday, October 19, 2014 11:46 PM
To: 
"openstack-operators@lists.openstack.org<mailto:openstack-operators@lists.openstack.org>"
 
<openstack-operators@lists.openstack.org<mailto:openstack-operators@lists.openstack.org>>
Subject: Re: [Openstack-operators] qemu 1.x to 2.0

We have the same setup (Icehouse on Ubuntu 12.04) and had similar issues. We 
downgraded qemu from 2.x to 1.x, as we cannot terminate all VMs for all users. 
We had non-resumable VMs also in the middle of the 1.x series and nothing was 
documented in the changlelog.
We had to do the same downgrade with openvswitch, the newest version, under 
heavy load, corrupts packets in-transit, but we do not have the time to 
investigate the issue further.

We plan to warn our users in time for the next major upgrade to Juno that all 
VMs need to be terminated, probably during the Christmas holidays. I do not 
think they will be happy.
Seeing also all the problems we had upgrading Neutron from OVS to ML2, 
terminating all VMs is probably the best policy anyway during an OpenStack 
upgrade. Or you do lots of migrations and upgrade qemu one compute host at the 
time, but if something goes wrong you end-up with an angry user and a stuck VM.

It certainly is a big deal.

On 10/20/14 00:59, Joe Topjian wrote:
Hello,

We recently upgraded an OpenStack Grizzly environment to Icehouse (doing a 
quick stop-over at Havana). This environment is still running Ubuntu 12.04.

The Ubuntu 14.04 release 
notes<https://wiki.ubuntu.com/TrustyTahr/ReleaseNotes#Ubuntu_Server> make 
mention of incompatibilities with 12.04 and moving to 14.04 and qemu 2.0. I 
didn't think that this would apply for upgrades staying on 12.04, but it indeed 
does.

We found that existing instances could not be live migrated (as per the release 
notes). Additionally, instances that were hard-rebooted and had the libvirt xml 
file rebuilt could no longer start, either.

The exact error message we saw was:

"Length mismatch: vga.vram: 1000000 in != 800000"

I found a few bugs that are related to this, but I don't think they're fully 
relevant to the issue I ran into:

https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1308756
https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1291321
https://bugs.launchpad.net/nova/+bug/1312133

We ended up downgrading to the stock Ubuntu 12.04 qemu 1.0 packages and 
everything is working nicely.

I'm wondering if anyone else has run into this issue and how they dealt with it 
or plan to deal with it.

Also, I'm curious as to why exactly qemu 1.x to 2.0 are incompatible with each 
other. Is this just an Ubuntu issue? Or is this native of qemu?

Unless I'm missing something, this seems like a big deal. If we continue to use 
Ubuntu's OpenStack packages, we're basically stuck at 12.04 and Icehouse unless 
we have all users snapshot their instance and re-launch in a new cloud.

Thanks,
Joe




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