[pgpool-general: 5327] Re: URGENT: Split-brain scenario...how to prevent?

Lazaro Garcia lazaro3487 at gmail.com
Sat Feb 11 01:32:16 JST 2017

Is fail_over_on_backend_error on or off?


Try with off?




De: pgpool-general-bounces at pgpool.net
[mailto:pgpool-general-bounces at pgpool.net] En nombre de David Sisk -X (dsisk
Enviado el: viernes, 10 de febrero de 2017 05:00 p. m.
Para: pgpool-general at pgpool.net
Asunto: [pgpool-general: 5325] Re: URGENT: Split-brain scenario...how to
Importancia: Alta


Can anyone provide any insight into how to prevent this split brain scenario
from happening?  Any responses appreciated.


Thanks and regards,

Dave Sisk





From: pgpool-general-bounces at pgpool.net
<mailto:pgpool-general-bounces at pgpool.net>
[mailto:pgpool-general-bounces at pgpool.net] On Behalf Of David Sisk -X (dsisk
Sent: Thursday, February 9, 2017 2:38 PM
To: pgpool-general at pgpool.net <mailto:pgpool-general at pgpool.net> 
Subject: [pgpool-general: 5321] URGENT: Split-brain scenario...how to


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).


1)      Auto-failover occurred, original standby is now primary.

2)      Prior primary/eminent standby at status 3 NOT reset/sync'd in any
way yet (not replicating and not in standby mode).

3)      pcp_attach_node 0 not only attaches the faulty standby, it actually
promotes the faulty standby back to primary! :-0


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.


Here are the health checks I have defined:

health_check_period = 10# NON-DEFAULT

health_check_timeout = 20

health_check_user = 'postgres'  # NON-DEFAULT

health_check_password = 'postgres'  # NON-DEFAULT

health_check_database = ''

health_check_max_retries = 2# NON-DEFAULT

health_check_retry_delay = 10# NON-DEFAULT


*  Not sure if this is used for load-balancing only, or also used to manage
node status

sr_check_period = 10

sr_check_user = 'postgres'  # NON-DEFAULT

sr_check_password = 'postgres'  # NON-DEFAULT

sr_check_database = 'postgres'

delay_threshold = 100000# NON-DEFAULT







David Sisk

Engineer - Software

 <mailto:dsisk at cisco.com> dsisk at cisco.com


Cisco Systems, Inc.

7025-6 Kit Creek Road PO Box 14987
United States



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