[Openstack-operators] qemu 1.x to 2.0

Joe Topjian joe at topjian.net
Sun Oct 19 22:59:26 UTC 2014


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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