[ClusterLabs] How to check if a resource on a cluster node is really back on after a crash
Ken Gaillot
kgaillot at redhat.com
Fri May 12 19:22:22 UTC 2017
Another possibility you might want to look into is alerts. Pacemaker can
call a script of your choosing whenever a resource is started or
stopped. See:
http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#idm139683940283296
for the concepts, and the pcs man page for the "pcs alert" interface.
On 05/12/2017 06:17 AM, Ludovic Vaugeois-Pepin wrote:
> I checked the node_state of the node that is killed and brought back
> (test3). in_ccm == true and crmd == online for a second or two between
> "pcs cluster start test3" "monitor":
>
> <node_state id="3" uname="test3" in_ccm="true" crmd="online"
> crm-debug-origin="peer_update_callback" join="member" expected="member">
>
>
>
> On Fri, May 12, 2017 at 11:27 AM, Ludovic Vaugeois-Pepin
> <ludovicvp at gmail.com <mailto:ludovicvp at gmail.com>> wrote:
>
> Yes I haven't been using the "nodes" element in the XML, only the
> "resources" element. I couldn't find "node_state" elements or
> attributes in the XML, so after some searching I found that it is in
> the CIB that can be gotten with "pcs cluster cib foo.xml". I will
> start exploring this as an alternative to crm_mon/"pcs status".
>
>
> However I still find what happens to be confusing, so below I try to
> better explain what I see:
>
>
> Before "pcs cluster start test3" at 10:45:36.362 (test3 has been HW
> shutdown a minute ago):
>
> crm_mon -1:
>
> Stack: corosync
> Current DC: test1 (version 1.1.15-11.el7_3.4-e174ec8) -
> partition with quorum
> Last updated: Fri May 12 10:45:36 2017 Last change: Fri
> May 12 09:18:13 2017 by root via crm_attribute on test1
>
> 3 nodes and 4 resources configured
>
> Online: [ test1 test2 ]
> OFFLINE: [ test3 ]
>
> Active resources:
>
> Master/Slave Set: pgsql-ha [pgsqld]
> Masters: [ test1 ]
> Slaves: [ test2 ]
> pgsql-master-ip (ocf::heartbeat:IPaddr2): Started
> test1
>
>
> crm_mon -X:
>
> <resources>
> <clone id="pgsql-ha" multi_state="true" unique="false"
> managed="true" failed="false" failure_ignored="false" >
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Master" active="true" orphaned="false" managed="true" f
> ailed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Slave" active="true" orphaned="false" managed="true" fa
> iled="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test2" id="2" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Stopped" active="false" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="0" />
> </clone>
> <resource id="pgsql-master-ip"
> resource_agent="ocf::heartbeat:IPaddr2" role="Started" active="true"
> orphaned="false" managed
> ="true" failed="false" failure_ignored="false"
> nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> </resources>
>
>
>
> At 10:45:39.440, after "pcs cluster start test3", before first
> "monitor" on test3 (this is where I can't seem to know that
> resources on test3 are down):
>
> crm_mon -1:
>
> Stack: corosync
> Current DC: test1 (version 1.1.15-11.el7_3.4-e174ec8) -
> partition with quorum
> Last updated: Fri May 12 10:45:39 2017 Last change: Fri
> May 12 10:45:39 2017 by root via crm_attribute on test1
>
> 3 nodes and 4 resources configured
>
> Online: [ test1 test2 test3 ]
>
> Active resources:
>
> Master/Slave Set: pgsql-ha [pgsqld]
> Masters: [ test1 ]
> Slaves: [ test2 test3 ]
> pgsql-master-ip (ocf::heartbeat:IPaddr2): Started
> test1
>
>
> crm_mon -X:
>
> <resources>
> <clone id="pgsql-ha" multi_state="true" unique="false"
> managed="true" failed="false" failure_ignored="false" >
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Master" active="true" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Slave" active="true" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test2" id="2" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Slave" active="true" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test3" id="3" cached="false"/>
> </resource>
> </clone>
> <resource id="pgsql-master-ip"
> resource_agent="ocf::heartbeat:IPaddr2" role="Started" active="true"
> orphaned="false" managed="true" failed="false"
> failure_ignored="false" nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> </resources>
>
>
>
> At 10:45:41.606, after first "monitor" on test3 (I can now tell the
> resources on test3 are not ready):
>
> crm_mon -1:
>
> Stack: corosync
> Current DC: test1 (version 1.1.15-11.el7_3.4-e174ec8) -
> partition with quorum
> Last updated: Fri May 12 10:45:41 2017 Last change: Fri
> May 12 10:45:39 2017 by root via crm_attribute on test1
>
> 3 nodes and 4 resources configured
>
> Online: [ test1 test2 test3 ]
>
> Active resources:
>
> Master/Slave Set: pgsql-ha [pgsqld]
> Masters: [ test1 ]
> Slaves: [ test2 ]
> pgsql-master-ip (ocf::heartbeat:IPaddr2): Started
> test1
>
>
> crm_mon -X:
>
> <resources>
> <clone id="pgsql-ha" multi_state="true" unique="false"
> managed="true" failed="false" failure_ignored="false" >
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Master" active="true" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Slave" active="true" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="1" >
> <node name="test2" id="2" cached="false"/>
> </resource>
> <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> role="Stopped" active="false" orphaned="false" managed="true"
> failed="false" failure_ignored="false" nodes_running_on="0" />
> </clone>
> <resource id="pgsql-master-ip"
> resource_agent="ocf::heartbeat:IPaddr2" role="Started" active="true"
> orphaned="false" managed="true" failed="false"
> failure_ignored="false" nodes_running_on="1" >
> <node name="test1" id="1" cached="false"/>
> </resource>
> </resources>
>
> On Fri, May 12, 2017 at 12:45 AM, Ken Gaillot <kgaillot at redhat.com
> <mailto:kgaillot at redhat.com>> wrote:
>
> On 05/11/2017 03:00 PM, Ludovic Vaugeois-Pepin wrote:
> > Hi
> > I translated the a Postgresql multi state RA
> > (https://github.com/dalibo/PAF) in Python
> > (https://github.com/ulodciv/deploy_cluster
> <https://github.com/ulodciv/deploy_cluster>), and I have been
> editing it
> > heavily.
> >
> > In parallel I am writing unit tests and functional tests.
> >
> > I am having an issue with a functional test that abruptly
> powers off a
> > slave named says "host3" (hot standby PG instance). Later on I
> start the
> > slave back. Once it is started, I run "pcs cluster start
> host3". And
> > this is where I start having a problem.
> >
> > I check every second the output of "pcs status xml" until
> host3 is said
> > to be ready as a slave again. In the following I assume that
> test3 is
> > ready as a slave:
> >
> > <nodes>
> > <node name="test1" id="1" online="true" standby="false"
> > standby_onfail="false" maintenance="false" pending="false"
> > unclean="false" shutdown="false" expected_up="true" is_dc="false"
> > resources_running="2" type="member" />
> > <node name="test2" id="2" online="true" standby="false"
> > standby_onfail="false" maintenance="false" pending="false"
> > unclean="false" shutdown="false" expected_up="true" is_dc="true"
> > resources_running="1" type="member" />
> > <node name="test3" id="3" online="true" standby="false"
> > standby_onfail="false" maintenance="false" pending="false"
> > unclean="false" shutdown="false" expected_up="true" is_dc="false"
> > resources_running="1" type="member" />
> > </nodes>
>
> The <nodes> section says nothing about the current state of the
> nodes.
> Look at the <node_state> entries for that. in_ccm means the cluster
> stack level, and crmd means the pacemaker level -- both need to
> be up.
>
> > <resources>
> > <clone id="pgsql-ha" multi_state="true" unique="false"
> > managed="true" failed="false" failure_ignored="false" >
> > <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> > role="Slave" active="true" orphaned="false" managed="true"
> > failed="false" failure_ignored="false" nodes_running_on="1" >
> > <node name="test3" id="3" cached="false"/>
> > </resource>
> > <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> > role="Master" active="true" orphaned="false" managed="true"
> > failed="false" failure_ignored="false" nodes_running_on="1" >
> > <node name="test1" id="1" cached="false"/>
> > </resource>
> > <resource id="pgsqld" resource_agent="ocf::heartbeat:pgha"
> > role="Slave" active="true" orphaned="false" managed="true"
> > failed="false" failure_ignored="false" nodes_running_on="1" >
> > <node name="test2" id="2" cached="false"/>
> > </resource>
> > </clone>
> > By ready to go I mean that upon running "pcs cluster start test3", the
> > following occurs before test3 appears ready in the XML:
> >
> > pcs cluster start test3
> > monitor-> RA returns unknown error (1)
> > notify/pre-stop -> RA returns ok (0)
> > stop -> RA returns ok (0)
> > start-> RA returns ok (0)
> >
> > The problem I have is that between "pcs cluster start test3" and
> > "monitor", it seems that the XML returned by "pcs status xml" says test3
> > is ready (the XML extract above is what I get at that moment). Once
> > "monitor" occurs, the returned XML shows test3 to be offline, and not
> > until the start is finished do I once again have test3 shown as ready.
> >
> > I am getting anything wrong? Is there a simpler or better way to check
> > if test3 is fully functional again, ie OCF start was successful?
> >
> > Thanks
> >
> > Ludovic
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