[Openstack] Quantum dhcp-agent getting out of sync with multiple instance launch / termination

Markku Tavasti markku.tavasti at cybercom.com
Wed Oct 9 13:57:24 UTC 2013

We are running grizzly-based, RedHat RDO.


On 10/09/2013 04:50 PM, Gary Kotton wrote:
> Hi,
> Which version are you using?
> Thanks
> Gary
> On 10/9/13 4:34 PM, "Markku Tavasti" <markku.tavasti at cybercom.com> wrote:
>> I found out that quantum dhcp agent gets out of sync when many instances
>> are launched or deleted same time. As a result, dnsmasq host-file have
>> lines missing (all launched are not added), or some lines aren't removed
>> when they should. When same ip is re-used, remaining extra lines aren't
>> removed, but same ip has two lines, and dhcp discoveries get no response
>> (no address available error on dnsmasq logs).
>> Restarting quantum-dhcp-agent will get everything back to proper state,
>> but running restart on cron every minute does not sound proper fix :-(
>> On my test, creating 16 instances, 2-3 of them did not get line in
>> host-file. When removing all those 16, 3-5 false lines were left behind.
>> On instance creation I see following message on quantum-server.log:
>> For every instance:
>> WARNING [quantum.db.agentschedulers_db] Fail scheduling network
>> {'status': u'ACTIVE', 'subnets':
>> [u'e9299278-bd49-4dc8-8df1-25b034f3ecea'], 'name': u'pk_tunk2',
>> 'provider:physical_network': u'vlans-osprv', 'admin_state_up': True,
>> 'tenant_id': u'06b9c423e10741ef83877b56d7608d7f',
>> 'provider:network_type': u'vlan', 'router:external': False, 'shared':
>> False, 'id': u'cbce52ef-58ba-4f3c-96fb-9d51bdbf32fb',
>> 'provider:segmentation_id': 427L}
>> However, network ports get created, and seems to work?
>> And most likely related to missing lines on host file on creation:
>> WARNING [quantum.scheduler.dhcp_agent_scheduler] No active DHCP agents
>> For termination of instances there is no warning or error messages.
>> Any ideas for fixing the situation?
>> --Tavasti
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