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<p class="MsoNormal"><a name="_MailEndCompose"><span style="color:#1F497D">Can anyone provide any insight into how to prevent this split brain scenario from happening? Any responses appreciated.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="color:#1F497D"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="color:#1F497D">Thanks and regards,<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="color:#1F497D">Dave Sisk<o:p></o:p></span></span></p>
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<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="color:#1F497D"><o:p> </o:p></span></span></p>
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<p class="MsoNormal"><b>From:</b> pgpool-general-bounces@pgpool.net [mailto:pgpool-general-bounces@pgpool.net]
<b>On Behalf Of </b>David Sisk -X (dsisk - TEKSYSTEMS INC at Cisco)<br>
<b>Sent:</b> Thursday, February 9, 2017 2:38 PM<br>
<b>To:</b> pgpool-general@pgpool.net<br>
<b>Subject:</b> [pgpool-general: 5321] URGENT: Split-brain scenario...how to prevent?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi folks…PGPool 3.5.4 with Postgres 9.3, streaming replication mode with primary and one standby. I found a scenario that caused a split-brain (luckily, it’s in a lab environment instead of a prod environment).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">1)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Auto-failover occurred, original standby is now primary.<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">2)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Prior primary/eminent standby at status 3 NOT reset/sync’d in any way yet (not replicating and not in standby mode).<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">3)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>pcp_attach_node 0 not only attaches the faulty standby, it actually promotes the faulty standby back to primary! :-0<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What configuration parameters will prevent this from happening? I’d prefer to get an error from pcp_attach_node and/or have the node stay at status 3.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are the health checks I have defined:<o:p></o:p></p>
<p class="MsoNormal">health_check_period = 10# NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">health_check_timeout = 20<o:p></o:p></p>
<p class="MsoNormal">health_check_user = 'postgres' # NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">health_check_password = 'postgres' # NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">health_check_database = ''<o:p></o:p></p>
<p class="MsoNormal">health_check_max_retries = 2# NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">health_check_retry_delay = 10# NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo4"><![if !supportLists]><span style="font-family:Wingdings"><span style="mso-list:Ignore">n<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>Not sure if this is used for load-balancing only, or also used to manage node status<o:p></o:p></p>
<p class="MsoNormal">sr_check_period = 10<o:p></o:p></p>
<p class="MsoNormal">sr_check_user = 'postgres' # NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">sr_check_password = 'postgres' # NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal">sr_check_database = 'postgres'<o:p></o:p></p>
<p class="MsoNormal">delay_threshold = 100000# NON-DEFAULT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666">David Sisk</span></b><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666">Engineer - Software<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666"><a href="mailto:dsisk@cisco.com"><span style="color:#666666;text-decoration:none">dsisk@cisco.com</span></a></span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666">Tel:
<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666">Cisco Systems, Inc.<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:#666666">7025-6 Kit Creek Road PO Box 14987<br>
RESEARCH TRIANGLE PARK<br>
27709-4987<br>
United States<br>
cisco.com<o:p></o:p></span></p>
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