[ClusterLabs] Question on restart of resource during fail over

Reid Wahl nwahl at redhat.com
Wed Dec 2 20:19:43 EST 2020


How did you resolve the issue? I see a problem in the CIB, and it may
be related to the issue you encountered. Even if not, it may cause
other issues later.

You have the following resource group:

      <group id="halvm">
        <primitive class="ocf" id="ClusterIP" provider="heartbeat"
type="IPaddr2">
        </primitive>
        <primitive class="ocf" id="halvmd" provider="heartbeat" type="LVM">
        </primitive>
        <primitive class="ocf" id="clxfs" provider="heartbeat"
type="Filesystem">
        </primitive>
        <primitive class="ocf" id="db2inst" provider="db2luwacademy"
type="db2server">
        </primitive>
      </group>

You have the following colocation constraint set:

      <rsc_colocation id="colocation_set_dthdcs" score="INFINITY">
        <resource_set id="colocation_set_dthdcs_set">
          <resource_ref id="db2inst"/>
          <resource_ref id="halvmd"/>
          <resource_ref id="clxfs"/>
          <resource_ref id="ClusterIP"/>
        </resource_set>
      </rsc_colocation>

The group says "place ClusterIP, then place halvmd, then place clxfs,
then place db2inst".
The constraint set says "place db2inst, then place halvmd, then place
clxfs, then place ClusterIP"[1].

A resource group is already an implicit set of ordering and colocation
constraints[2]. If you're happy with the order configured in the
resource group, then you should remove the colocation_set_dthdcs
constraint.

[1] Example 5.15. Equivalent colocation chain expressed using
resource_set (https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/2.0/html-single/Pacemaker_Explained/index.html#idm46061107170640)
[2] ⁠10.1. Groups - A Syntactic Shortcut
(https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/2.0/html-single/Pacemaker_Explained/index.html#group-resources)

On Wed, Dec 2, 2020 at 4:01 AM Harishkumar Pathangay
<harishpathangay at outlook.com> wrote:
>
> Hi,
>
> I realized it can be used in standard mode only after you pointing to that.
>
> Anyways, writing custom agent always gives me a good understanding of the resources start/stop/monitor etc…
>
> My custom agent still has lot of “hard coded” values, but it is meant for studying and understanding purposes rather than to put in a production machine.
>
>
>
> Please find attachments.
>
>
>
> Thanks,
>
> Harish P
>
>
>
> Sent from Mail for Windows 10
>
>
>
> From: Reid Wahl
> Sent: 02 December 2020 15:55
> To: Cluster Labs - All topics related to open-source clustering welcomed
> Subject: Re: [ClusterLabs] Question on restart of resource during fail over
>
>
>
> On Wed, Dec 2, 2020 at 2:16 AM Harishkumar Pathangay
> <harishpathangay at outlook.com> wrote:
> >
> > Just got the issue resolved.
>
> Nice work!
>
> > Any case I will send the cib.xml and my custom db2 resource agent.
> >
> > The existing resource agent is for HADR database, where there are two databases one running as Primary and other as standby.
>
> HADR is only one option. There's also a standard mode:
>   - https://github.com/oalbrigt/resource-agents/blob/master/heartbeat/db2#L64-L69
>
> I don't know much about DB2, so I'm not sure whether that would meet
> your needs. Based on the metadata, standard mode appears to manage a
> single instance (with the databases you select) on one node at a time.
>
> > I have created a script which will start/stop db2 instances with a single database on shared logical volume [HA-LVM] exclusively activated on one node.
> >
> >
> >
> > Will mail you shortly.
> >
> >
> >
> > Thanks,
> >
> > Harish P
> >
> >
> >
> > Sent from Mail for Windows 10
> >
> >
> >
> > From: Reid Wahl
> > Sent: 02 December 2020 12:46
> > To: Cluster Labs - All topics related to open-source clustering welcomed
> > Subject: Re: [ClusterLabs] Question on restart of resource during fail over
> >
> >
> >
> > Can you share your pacemaker configuration (i.e.,
> > /var/lib/pacemaker/cib/cib.xml)? If you're concerned about quorum,
> > then also share your /etc/corosync/corosync.conf just in case.
> >
> > Also there's a db2 resource agent already written, if you're interested:
> > - https://github.com/oalbrigt/resource-agents/blob/master/heartbeat/db2
> >
> > On Tue, Dec 1, 2020 at 9:50 AM Harishkumar Pathangay
> > <harishpathangay at outlook.com> wrote:
> > >
> > > Hi,
> > >
> > > I have DB2 resource agent scripted by myself.
> > >
> > > It is working fine with a small glitch.
> > >
> > >
> > >
> > > I have node1 and node2 in the cluster. No stonith enabled as I don't need one. The environment is for learning purpose only.
> > >
> > >
> > >
> > > If node one is down [power off], it is starting the resource on other node which is good. My custom resource agent doing its job. Let us say DB2 is running with pid 4567.
> > >
> > >
> > >
> > > Now, the original node which went down is back again.  I issue “pcs cluster start” on the node. Node is online. The resource also stays in the other node, which is again good. That way unnecessary movement of resources is avoided, exactly what I want. Good but there is a issue.
> > >
> > > On the other node it is restarting the DB2 resource. So my pid of db2 changes to 3452.
> > >
> > > This is unnecessary restart of resource which I want to avoid.
> > >
> > > How to I get this working.
> > >
> > >
> > >
> > > I am very new to cluster pacemaker.
> > >
> > > Please help me so that I can create a working DB2 cluster for my learning purpose.
> > >
> > > Also I will be blogging in my youtube channel DB2LUWACADEMY.
> > >
> > > Please any help is of great significance to me.
> > >
> > >
> > >
> > > I think it could be quorum issue. But don't know for sure, because there is only two nodes and DB2 resource needs to be active only in one node.
> > >
> > >
> > >
> > > How do I get this configured.
> > >
> > >
> > >
> > > Thanks.
> > >
> > > Harish P
> > >
> > >
> > >
> > >
> > >
> > > Sent from Mail for Windows 10
> > >
> > >
> > >
> > > _______________________________________________
> > > Manage your subscription:
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> > >
> > > ClusterLabs home: https://www.clusterlabs.org/
> >
> >
> >
> > --
> > Regards,
> >
> > Reid Wahl, RHCA
> > Senior Software Maintenance Engineer, Red Hat
> > CEE - Platform Support Delivery - ClusterHA
> >
> > _______________________________________________
> > Manage your subscription:
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> >
> > ClusterLabs home: https://www.clusterlabs.org/
> >
> >
> >
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> >
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>
>
>
> --
> Regards,
>
> Reid Wahl, RHCA
> Senior Software Maintenance Engineer, Red Hat
> CEE - Platform Support Delivery - ClusterHA
>
> _______________________________________________
> Manage your subscription:
> https://lists.clusterlabs.org/mailman/listinfo/users
>
> ClusterLabs home: https://www.clusterlabs.org/
>
>
>
> _______________________________________________
> Manage your subscription:
> https://lists.clusterlabs.org/mailman/listinfo/users
>
> ClusterLabs home: https://www.clusterlabs.org/



-- 
Regards,

Reid Wahl, RHCA
Senior Software Maintenance Engineer, Red Hat
CEE - Platform Support Delivery - ClusterHA



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