[Pacemaker] Configuring 3rd Node as Quorum Node in 2 Node Cluster

Andrew Martin amartin at xes-inc.com
Wed Mar 7 14:38:32 UTC 2012


Hi Andrew, 


I've installed pacemaker and updated my ha.cf on the quorum node, removing ccm and replacing it with the pacemaker respawn line. You're correct - migration happens quickly and does not need to wait for these timeouts. I then reverted crmd-integration-timeout to its default 3m value. 


Thanks, 


Andrew 

----- Original Message -----

From: "Andrew Beekhof" < andrew at beekhof.net > 
To: "The Pacemaker cluster resource manager" < pacemaker at oss.clusterlabs.org > 
Sent: Monday, February 27, 2012 5:25:46 AM 
Subject: Re: [Pacemaker] Configuring 3rd Node as Quorum Node in 2 Node Cluster 

It looks like we're waiting for the other node to respond, which it wont do. 
Is running pacemaker on the other node but with standby=true an option for you? 

On Sat, Feb 25, 2012 at 6:25 AM, Andrew Martin < amartin at xes-inc.com > wrote: 
> 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 
> 
> ________________________________ 
> 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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>> 
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> 
> 
> 
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