Hi,<div><br></div><div>In the case you describe below, using DISALLOW_TO_FAILOVER what is the purpose of the Watchdog?</div><div><br></div><div>I have noticed pcp commands which alter node state are at least propagated.<span></span></div>
<div><br></div><div>Cheers,</div><div>James<br><br>On Thursday, 26 June 2014, Yugo Nagata <<a href="mailto:nagata@sraoss.co.jp">nagata@sraoss.co.jp</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<br>
On Mon, 23 Jun 2014 16:33:35 +1000<br>
James Sewell <<a href="javascript:;" onclick="_e(event, 'cvml', 'james.sewell@lisasoft.com')">james.sewell@lisasoft.com</a>> wrote:<br>
<br>
> Hello All,<br>
><br>
> I have a load balancer in front of a pair of pgpool nodes (3.3.1), in front<br>
> of a pair of PostgreSQL nodes (9.3) which are configured as a streaming<br>
> pair. I am running on RHEL.<br>
><br>
> I am using another HA tool to manage the failover between the Postgres<br>
> nodes, and the load is spread between the pgpool nodes with inactive nodes<br>
> being taken out of the load balanced pool.<br>
><br>
> Do I need watchdog in this case? I have seen reports that pgpool still<br>
> synchronises useful information using this connection, but can't find what<br>
> this information is?<br>
><br>
> If I did use watchdog, which settings would I need in this limited case?<br>
<br>
When watchdog enabled, backend status is shared between pgpools.<br>
For example, when backend goes down ** and when a pgpool detects<br>
this and handles the failover **, the backend status change is sent<br>
to another pgpool.<br>
<br>
However, if you use another HA tools to protecte backends, you might<br>
want to use DIALLOW_TO_FAILOVER flag in backend_flag.<br>
<a href="http://www.pgpool.net/docs/latest/pgpool-en.html#BACKEND_FLAG" target="_blank">http://www.pgpool.net/docs/latest/pgpool-en.html#BACKEND_FLAG</a><br>
If you use DIALLOW_TO_FAILOVER, the backend status change wouldn't<br>
be sent to another pgpool, since pgpool doesn't handle backend failover.<br>
<br>
And in your case, delegate_IP should be empty since virtual IP sn't necessary.<br>
<br>
><br>
> Also is there a pcp command which I can use to tell pgpool that a new node<br>
> is master, but not actually promote it (this would have happened already)?<br>
> Does pcp_promote_node do this when no promotion script is provided?<br>
<br>
pcp_promote_node works as follow:<br>
<br>
(1) This changes pgpool-II's internal status and set the specified<br>
node to primary. The internal status is used in online-recovery<br>
and loadbalancing etc..<br>
** Note that this doesn't control the backend nodes themselves.**<br>
<br>
(2) All nodes other than the new primary are detached from pgpool-II.<br>
<br>
(3) pgpool-II execute follow_master command for all the detached nodes.<br>
<br>
<br>
As mentioned at (1), pcp_promote_node doesn't actually promote bacend node.<br>
However, please note that pcp_promote_node detaches all nodes other than the<br>
new primary. You would have to execute pcp_attach_node to attach the nodes in<br>
follow_master command.<br>
<br>
When watchdog enabled, backend status changes by pcp_promote_node and<br>
pcp_attach_node also are sent to another pgpool.<br>
<br>
><br>
> Thanks for the help.<br>
><br>
> Cheers,<br>
><br>
> James Sewell,<br>
> Solutions Architect<br>
> ______________________________________<br>
><br>
><br>
> Level 2, 50 Queen St, Melbourne VIC 3000<br>
><br>
> *P *(+61) 3 8370 8000 *W* <a href="http://www.lisasoft.com" target="_blank">www.lisasoft.com</a> *F *(+61) 3 8370 8099<br>
><br>
> --<br>
><br>
><br>
> ------------------------------<br>
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<br>
<br>
--<br>
Yugo Nagata <<a href="javascript:;" onclick="_e(event, 'cvml', 'nagata@sraoss.co.jp')">nagata@sraoss.co.jp</a>><br>
</blockquote></div><br><br>-- <br><div style="color:#b8276a;font:bold 14px Arial,Helvetica,sans-serif">
<br>
<span style="color:#323b62">James Sewell,</span><br>
<span style="color:#a9a9a9"><span style="font:12px Arial,Helvetica,sans-serif">PostgreSQL Team Lead / Solutions Architect </span></span><br>
<span style="color:#a9a9a9">______________________________________</span><br>
</div>
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