[Pacemaker] pre_notify_demote is issued twice

[Andrew Beekhof]

On 18 Feb 2014, at 1:23 pm, Andrew Beekhof <andrew at beekhof.net> wrote:

> 
> On 6 Feb 2014, at 7:45 pm, Keisuke MORI <keisuke.mori+ha at gmail.com> wrote:
> 
>> Hi,
>> 
>> I observed that pre_notify_demote is issued twice when a master
>> resource is migrating.
>> I'm wondering if this is the correct behavior.
>> 
>> Steps to reproduce:
>> 
>> - Start up 2 nodes cluster configured for the PostgreSQL streaming
>> replication using pgsql RA as  a master/slave resource.
>> - kill the postgresql process on the master node to induce a fail-over.
>> - The fail-over succeeds as expected, but pre_notify_demote was
>> executed twice on each node before demoting on the master resource.
>> 
>> 100% reproducible on my cluster.
>> 
>> Pacemaker version: 1.1.11-rc4 (source build from the repo)
>> OS: RHEL6.4
>> 
>> I have never seen this on Pacemaker-1.0.* cluster with the same configuration.
>> 
>> The relevant logs and pe-inputs are attached.
>> 
>> 
>> Diagnostics:
>> 
>> (1) The first transition caused by the process failure (pe-input-160)
>> initiates pre_notify_demote on both nodes and cancelling slave monitor
>> on the slave node.
>> {{{
>> 171 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>> Initiating action 9: cancel prmPostgresql_cancel_10000 on rhel64-2
>> 172 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>> Initiating action 79: notify prmPostgresql_pre_notify_demote_0 on
>> rhel64-1 (local)
>> 
>> 175 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>> Initiating action 81: notify prmPostgresql_pre_notify_demote_0 on
>> rhel64-2
>> }}}
>> 
>> (2) When cancelling slave monitor completes, the transition is aborted
>> by Resource op removal.
>> {{{
>> 176 Jan 30 16:08:59 rhel64-1 crmd[8143]:     info: match_graph_event:
>> Action prmPostgresql_monitor_10000 (9) confirmed on rhel64-2 (rc=0)
>> 177 Jan 30 16:08:59 rhel64-1 cib[8138]:     info: cib_process_request:
>> Completed cib_delete operation for section status: OK (rc=0,
>> origin=rhel64-2/crmd/21, version=0.37.9)
>> 178 Jan 30 16:08:59 rhel64-1 crmd[8143]:     info:
>> abort_transition_graph: te_update_diff:258 - Triggered transition
>> abort (complete=0, node=rhel64-2, tag=lrm_rsc_op,
>> id=prmPostgresql_monitor_10000,
>> magic=0:0;26:12:0:acf9a2a3-307c-460b-b786-fc20e6b8aad5, cib=0.37.9) :
>> Resource op removal
>> }}}
>> 
>> (3) The second transition is calculated by the abort (pe-input-161)
>> which results initiating pre_notify_demote again.
> 
> If the demote didn't complete (or wasn't even attempted), then we must send the pre_notify_demote again unfortunately.
> The real bug may well be that the transition shouldn't have been aborted.

It looks legitimate:

Jan 30 16:08:59 rhel64-1 crmd[8143]:     info: abort_transition_graph: te_update_diff:258 - Triggered transition abort (complete=0, node=rhel64-2, tag=lrm_rsc_op, id=prmPostgresql_monitor_10000, magic=0:0;26:12:0:acf9a2a3-307c-460b-b786-fc20e6b8aad5, cib=0.37.9) : Resource op removal

Jan 30 16:08:59 rhel64-1 cib[8138]:     info: cib_process_request: Completed cib_delete operation for section status: OK (rc=0, origin=rhel64-2/crmd/21, version=0.37.9)

It looks like part of the node status entry being removed for rhel64-2.
Possibly as a result of:

Jan 30 16:07:54 rhel64-2 crmd[25070]:     info: erase_status_tag: Deleting xpath: //node_state[@uname='rhel64-2']/transient_attributes

The new cib code, being much faster, might help here too :)

> 
>> {{{
>> 227 Jan 30 16:09:01 rhel64-1 pengine[8142]:   notice:
>> process_pe_message: Calculated Transition 15:
>> /var/lib/pacemaker/pengine/pe-input-161.bz2
>> 229 Jan 30 16:09:01 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>> Initiating action 78: notify prmPostgresql_pre_notify_demote_0 on
>> rhel64-1 (local)
>> 232 Jan 30 16:09:01 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>> Initiating action 80: notify prmPostgresql_pre_notify_demote_0 on
>> rhel64-2
>> }}}
>> 
>> I think that the transition abort at (2) should not happen.
>> 
>> Regards,
>> -- 
>> Keisuke MORI
>> <logs-pre-notify-20140206.tar.bz2>_______________________________________________
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> 

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