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Andrew Bogott's profile - activity

2020-08-28 14:02:38 -0500 answered a question nova-compute deadlocks after live migration

Rocky basically doesn't work on python3.7 (the version shipped on Debian Buster) because of issues with threading.

This is fixed in version Stein with the following patch:

There is no non-code workaround as far as I know.

2020-08-28 14:02:38 -0500 asked a question nova-compute deadlocks after live migration

With python version 3.7 and any nova version before Stein, live migration results in a deadlock.

I'm asking this question so I can answer it -- the fix is in place in Stein but a bug was never opened against Nova so it's pretty hard to diagnose.

2020-08-06 16:43:42 -0500 answered a question live migration failing with "Unexpected API Error"

I was seeing this problem recently; the issue turned out to be a timeout in the HAproxy in front of the nova api. Nova takes quite a while to muster a response to a migration request; when I changed my server timeout from 50s to 120s I started getting useful responses from my migration calls.

2020-08-06 16:43:42 -0500 answered a question Access to Horizon Dashboard Without Login

This isn't quite what you want, but we solved this problem by creating a publicly-viewable browser tool:

We haven't really considered third-party use of this, but the source is gpl3: (

2020-08-06 16:43:42 -0500 asked a question Understanding hypervisor compatibility during live migration

I've recently added ceph shared storage to my cloud, and I'm experimenting with live migration. I have two groups of hypervisors, one running Debian Buster and one running Debian Stretch. In order to ensure migration compatibility I've set this on all compute nodes:

cpu_mode=custom cpu_model=IvyBridge-IBRS

Nevertheless, nova will migrate hosts from my Stretch to Buster hosts but if I try to migrate something back from Buster to Stretch it tells me 'The instance requires a newer hypervisor version than has been provided.'

How can I determine what it means by 'newer'? Surely it doesn't actually care about the host OS; Both are running nova 'rocky.' The libvirt versions are different due to the distro differences.


  • nova-compute 2:18.1.0-6+deb10u1~bpo9+1
  • nova-compute-kvm 2:18.1.0-6+deb10u1~bpo9+1
  • libvirt-clients 4.3.0-1~bpo9+1.1


  • nova-compute 2:18.1.0-6+deb10u1~bpo10+1
  • nova-compute-kvm 2:18.1.0-6+deb10u1~bpo10+1
  • libvirt-clients 5.0.0-4+deb10u1

Can anyone advise me about how to support bi-directional migration? Or, failing that, help me understand what nova is upset about?

2020-07-31 20:08:43 -0500 answered a question Neutron failing to deploy with "Policy DROP not allowed for user defined chains."

I encountered the same issue, and oxy's suggestion seems to resolve the issue. For those who want to automate things, the one-line solution is:

# update-alternatives --set ebtables /usr/sbin/ebtables-legacy

2020-07-31 18:30:47 -0500 received badge  Supporter (source)