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Any comments/input on this?
Ajay


From: Ajay Kalambur <akalambu at cisco.com<mailto:akalambu at cisco.com>>
Date: Monday, October 10, 2016 at 6:31 PM
To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: [openstack][nova] Port unbound from active VM

Hi
There seems to be a corner case bug in nova code. Steps to reproduce it are

  1.  Create a neutron port
  2.  Create a VM and launch instance with this port
  3.  Shutdown nova compute and network agent on compute node
  4.  Unbind port from VM and delete the VM (offline delete)
  5.  Now create a VM with same port but on a different compute node
  6.  Bring up nova compute on old node

It basically runs the reap for deleted instances and cleanes up VM from libvirt. In the process it unbinds the pre-existing ports and ends up unbinding the port from an active VM on a different compute node
Reason nova simply sends a blind port-update with binding_host: “” even if that port is bound to a different instance


So following fix seemed to help any suggestions on a better fix

In nova/network/neutronv2/api.py. So basically when neutron sees no ports for this instance don’t attempt an unbind
In this case
data = neutron.list_ports(**search_opts)
Call in deallocate_for_instance returns empty ports




      # Reset device_id and device_owner for the ports that are skipped

        if data.get('ports', []):

            self._unbind_ports(context, ports_to_skip, neutron)

        else:

            LOG.debug("Neutron sees a different view of this port hence skipping unbind”)



Ajay

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