[Pacemaker] Configuring 3rd Node as Quorum Node in 2 Node Cluster
Andrew Martin
amartin at xes-inc.com
Fri Feb 24 19:25:42 UTC 2012
Hi Andreas,
Thanks, adding "respawn hacluster /usr/lib/heartbeat/ccm" to ha.cf worked. Since quorum-node is in standby, it shows up as "OFFLINE (standby)" in crm_mon. It seems that "cl_status nodestatus quorum-node" always returns "active", even if heartbeat is stopped on the quorum node. However, "cl_status hblinkstatus quorum-node br0" can correctly detect if heartbeat is down on quorum-node so I can use that to check its connectivity.
I was able to successfully test resources automatically stopping once quorum was lost. I did this by shutting down node2 so that only node1 and quorum-node remained. I then stopped heartbeat on quorum-node, which resulted in node1 losing quorum and the resources stopping (as expected). After starting heartbeat on quorum-node again, node1 reestablished quorum within about 1 minute. However, it took significantly longer (around 18 minutes) for the resources on node1 to start again. Looking through the logs, I discovered that this is because of the values of the cluster-recheck-interval (displayed as "PEngine Recheck Timer" in the logs) and crmd-integration-timeout (displayed as "Integration Timer" in the logs) properties. Here's the sequence of events as I understand it:
1. quorum is reestablished
2. the cluster-recheck-interval timer pops, sees that quorum has been reestablished, and schedules crmd-integration-timeout to run
3. after crmd-integration-timeout's timeout period, it pops and also sees that quorum has been restablished and thus starts the resources
Based on this, the maximum wait time for resources to start once quorum has been reestablished is the value of cluster-recheck-interval plus the value of crmd-integration-timeout, or (15m + 3m). I have confirmed this value through several runs of this test. This seems like a very long time to me, so I adjusted both of these values down to 1m. Running the test again I was able to confirm that the resources started 2m after quorum was reestablished:
## quorum reestablished
12:35:31 node1 ccm: [27015]: debug: quorum plugin: majority
12:35:31 node1 ccm: [27015]: debug: cluster:linux-ha, member_count=2, member_quorum_votes=200
12:35:31 node1 ccm: [27015]: debug: total_node_count=3, total_quorum_votes=300
12:35:31 node1 crmd: [27020]: info: crmd_ccm_msg_callback: Quorum (re)attained after event=NEW MEMBERSHIP (id=14)
12:35:31 node1 crmd: [27020]: info: crm_update_quorum: Updating quorum status to true (call=366)
## cluster-recheck-interval pops, schedules crmd-integration-timeout to run after its timout
12:36:18 node1 crmd: [27020]: info: crm_timer_popped: PEngine Recheck Timer (I_PE_CALC) just popped (60000ms)
12:36:18 node1 crmd: [27020]: info: do_state_transition: State transition S_IDLE -> S_POLICY_ENGINE [ input=I_PE_CALC cause=C_TIMER_POPPED origin=crm_timer_popped ]
12:36:18 node1 crmd: [27020]: info: do_state_transition: Progressed to state S_POLICY_ENGINE after C_TIMER_POPPED
## crmd-integration-timeout runs, starts the resources
12:37:18 node1 crmd: [27020]: ERROR: crm_timer_popped: Integration Timer (I_INTEGRATED) just popped in state S_INTEGRATION! (60000ms)
12:37:18 node1 crmd: [27020]: info: crm_timer_popped: Welcomed: 1, Integrated: 1
12:37:18 node1 crmd: [27020]: info: do_state_transition: State transition S_INTEGRATION -> S_FINALIZE_JOIN [ input=I_INTEGRATED cause=C_TIMER_POPPED origin=crm_timer_popped ]
12:37:18 node1 crmd: [27020]: WARN: do_state_transition: Progressed to state S_FINALIZE_JOIN after C_TIMER_POPPED
12:37:20 node1 crmd: [27020]: info: do_dc_join_final: Ensuring DC, quorum and node attributes are up-to-date
12:37:20 node1 crmd: [27020]: info: crm_update_quorum: Updating quorum status to true (call=379)
12:37:20 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r0:1#011(Stopped)
12:37:20 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r1:1#011(Stopped)
12:37:20 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r2:1#011(Stopped)
12:37:20 node1 pengine: [29916]: notice: LogActions: Leave p_libvirt-bin:1#011(Stopped)
12:37:20 node1 pengine: [29916]: notice: LogActions: Leave p_libvirt-bin:2#011(Stopped)
12:37:21 node1 crmd: [27020]: notice: run_graph: Transition 77 (Complete=24, Pending=0, Fired=0, Skipped=3, Incomplete=0, Source=/var/lib/pengine/pe-input-526.bz2): Stopped
12:37:21 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r0:1#011(Stopped)
12:37:21 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r1:1#011(Stopped)
12:37:21 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r2:1#011(Stopped)
12:37:21 node1 pengine: [29916]: notice: LogActions: Leave p_libvirt-bin:1#011(Stopped)
12:37:21 node1 pengine: [29916]: notice: LogActions: Leave p_libvirt-bin:2#011(Stopped)
12:37:23 node1 lrmd: [27017]: info: RA output: (p_vm:start:stdout) Domain MyVM started
12:38:23 node1 crmd: [27020]: info: crm_timer_popped: PEngine Recheck Timer (I_PE_CALC) just popped (60000ms)
12:38:23 node1 crmd: [27020]: info: do_state_transition: State transition S_IDLE -> S_POLICY_ENGINE [ input=I_PE_CALC cause=C_TIMER_POPPED origin=crm_timer_popped ]
12:38:23 node1 crmd: [27020]: info: do_state_transition: Progressed to state S_POLICY_ENGINE after C_TIMER_POPPED
12:38:23 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r0:1#011(Stopped)
12:38:23 node1 pengine: [29916]: notice: LogActions: Leave p_drbd_r1:1#011(Stopped)
I've attached the full logs from this time period in addition to the excerpt above.
Is there a better way to trigger the starting of resources once quorum has been reestablished? Or is modifying these two properties a good way of doing it?
Thanks,
Andrew
----- Original Message -----
From: "Andreas Kurz" < andreas at hastexo.com >
To: pacemaker at oss.clusterlabs.org
Sent: Friday, February 24, 2012 7:26:59 AM
Subject: Re: [Pacemaker] Configuring 3rd Node as Quorum Node in 2 Node Cluster
Hello,
On 02/23/2012 03:59 PM, Andrew Martin wrote:
> I set up the 3rd node ("quorum") yesterday by only installing heartbeat,
> not pacemaker. Is pacemaker necessary as well? I commented out the
> following lines in its ha.cf since it is always going to be running in
> standby:
> autojoin none
> mcast eth0 239.0.0.43 694 1 0
> bcast eth0
> warntime 5
> deadtime 15
> initdead 60
> keepalive 2
> node node1
> node node2
> node quorum
> #crm respawn
> #respawn hacluster /usr/lib/heartbeat/dopd
> #apiauth dopd gid=haclient uid=hacluster
>
Hmm ... IIRC I had to enable ccm in ha.cf on the third node during my
last heartbeat tests to enable a quorum node:
respawn hacluster ccm
> Since this quorum node only has a single ethernet interface, can it be
> used for both the mcast and bcast parameters? How are both the multicast
> and broadcast pathways used for node communication? After saving these
> parameters and reloading heartbeat on all nodes, the "quorum" node is
> listed as offline in the cluster. Is there something missing in my
> configuration that is preventing it from communicating with the rest of
> the cluster?
cl_status and hbclient should give you some membership information, and
there should be some log entries on the nodes running Pacemaker. I don't
think the node will show up as ONLINE in crm_mon if no Pacemaker is
running there.
You only need the communication settings you also used for node1/2 on
the shared network ... so only the mcast directive is needed/possible on
node3.
>
> Also, another more general question about the failover - node1 and node2
> are each connected to the shared network over br0 and connected directly
> to each other with a crossover cable over br1:
> -------------------- ----------
> | Shared Network |------| quorum |
> -------------------- ----------
> |
> br0 / \ br0
> / \
> --------- ---------
> | node1 | --------- | node2 |
> --------- br1 ---------
>
> The corresponding configuration in ha.cf is
> autojoin none
> mcast br0 239.0.0.43 694 1 0
> bcast br1
> warntime 5
> ....
>
> If br0 to one of the nodes were to be cut when the "quorum" node was
> down, would they still be able to communicate over br1 (e.g. to maintain
> quorum between themselves and fail over to the other node that still has
> an active br0)?
as long as node1/2 can communicate the cluster has quorum, to fail over
resources to the node with best connectivity: configure ping resource
agent and constraints, there is a chapter in "Pacemake Explained" on
clusterlabs.org ... http://goo.gl/x7dwK
Regards,
Andreas
--
Need help with Pacemaker?
http://www.hastexo.com/now
>
> Thanks,
>
> Andrew
>
> ------------------------------------------------------------------------
> *From: *"Andreas Kurz" < andreas at hastexo.com >
> *To: *pacemaker at oss.clusterlabs.org
> *Sent: *Monday, January 23, 2012 1:53:27 PM
> *Subject: *Re: [Pacemaker] Configuring 3rd Node as Quorum Node in
> 2 Node Cluster
>
> On 01/23/2012 03:36 PM, Andrew Martin wrote:
>> I think I will configure the 3rd (quorum) node in standby mode. In the
>> near future I am looking into setting up 2 additional clusters (each of
>> these are also 2-node clusters) and would like to use this same server
>> as the quorum node for those clusters as well. Is this possible? If so,
>> how do I have to configure heartbeat (or multiple instances of
>> heartbeat) to join multiple clusters at once and act as the quorum node
>> in each?
>
> No, multiple heartbeat instances per node are not supported ... but why
> not creating minimal VM instances ... though not to minimal, as you have
> a good chance that theses standby instances become DC role.
>
> Regards,
> Andreas
>
> --
> Need help with Pacemaker?
> http://www.hastexo.com/now
>
>>
>> Thanks,
>>
>> Andrew
>>
>> ------------------------------------------------------------------------
>> *From: *"Andreas Kurz" < andreas at hastexo.com >
>> *To: *pacemaker at oss.clusterlabs.org
>> *Sent: *Friday, January 13, 2012 6:35:48 AM
>> *Subject: *Re: [Pacemaker] Configuring 3rd Node as Quorum Node in 2
>> Node Cluster
>>
>> On 01/13/2012 12:32 PM, Ivan Savčić | Epix wrote:
>>> On 1/11/2012 8:28 AM, Florian Haas wrote:
>>>> Another option would be to permanently run the 3rd node in standby mode.
>>>
>>> Just wondering, wouldn't the standby mode prevent that node from
>>> performing the fencing actions? Also, can it act as DC then?
>>
>> It would run no resources (including stonith resources) but can be the DC.
>>
>> Another option for running a "pure" quorum node would be to only start
>> CCM but not pacemaker ... though that setup looks quite strange e.g. in
>> crm_mon output ....
>>
>> Regards,
>> Andreas
>>
>> --
>> Need help with Pacemaker?
>> http://www.hastexo.com/now
>>
>>>
>>> Thanks,
>>> Ivan
>>>
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>>
>>
>>
>>
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>
>
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