[ClusterLabs] Pacemaker quorum behavior

Jan Pokorný jpokorny at redhat.com
Fri Sep 9 17:55:35 EDT 2016

On 09/09/16 14:13 -0400, Scott Greenlese wrote:
> You had mentioned this command:
> pstree -p | grep -A5 $(pidof -x pcs)
> I'm not quite sure what the $(pidof -x pcs) represents??

This is a "command substitution" shell construct (new, blessed form
of `backtick` notation) that in this particular case was meant to
yield PID of running pcs command.  The whole compound command
was then meant to possibly discover what pcs is running under
the hood because that's what might get stuck.

> On an "Online" cluster node, I see:
> [root at zs93kj ~]# ps -ef |grep pcs |grep -v grep
> root      18876      1  0 Sep07 ?
> 00:00:00 /bin/sh /usr/lib/pcsd/pcsd start
> root      18905  18876  0 Sep07 ?        00:00:00 /bin/bash -c ulimit -S -c
> 0 >/dev/null 2>&1 ; /usr/bin/ruby -I/usr/lib/pcsd /usr/lib/pcsd/ssl.rb
> root      18906  18905  0 Sep07 ?        00:04:22 /usr/bin/ruby
> -I/usr/lib/pcsd /usr/lib/pcsd/ssl.rb
> [root at zs93kj ~]#
> If I use the 18876 PID on a healthy node, I get..
> [root at zs93kj ~]# pstree -p |grep -A5 18876
>            |-pcsd(18876)---bash(18905)---ruby(18906)-+-{ruby}(19102)
>            |                                         |-{ruby}(20212)
>            |                                         `-{ruby}(224258)
>            |-pkcsslotd(18851)
>            |-polkitd(19091)-+-{polkitd}(19100)
>            |                |-{polkitd}(19101)
> Is this what you meant for me to do?

Only if I got my guess about "pcs cluster stop" command stuck right,
which is not the case, as you explained.

> If so, I'll be sure to do that next time I suspect processes are not
> exiting on cluster kill or stop.

In this another case, you really want to consult "systemctl status X"
for X in (corosync, pacemaker).   And to be really sure, for instance,
"pgrep Y" for Y in (pacemakerd, crmd, corosync).

(I hope I didn't confuse you too much due to the mentioned wild
guess originally).

Jan (Poki)
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