[pgpool-general: 5332] Re: URGENT: Split-brain scenario...how to prevent?

David Sisk -X (dsisk - TEKSYSTEMS INC at Cisco) dsisk at cisco.com
Thu Feb 16 07:13:30 JST 2017


Tatsuo Ishii, Muhammad Usama...would one of you be kind enough to provide some kind of reply to this question?


Thank you in advance,

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David Sisk
Engineer - Software
dsisk at cisco.com<mailto:dsisk at cisco.com>
Tel:

Cisco Systems, Inc.
7025-6 Kit Creek Road PO Box 14987
RESEARCH TRIANGLE PARK
27709-4987
United States
cisco.com


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From: pgpool-general-bounces at pgpool.net [mailto:pgpool-general-bounces at pgpool.net] On Behalf Of David Sisk -X (dsisk - TEKSYSTEMS INC at Cisco)
Sent: Friday, February 10, 2017 11:00 AM
To: pgpool-general at pgpool.net
Subject: [pgpool-general: 5325] Re: URGENT: Split-brain scenario...how to prevent?
Importance: High

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 - TEKSYSTEMS INC at Cisco)
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 prevent?

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


n  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




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David Sisk
Engineer - Software
dsisk at cisco.com<mailto:dsisk at cisco.com>
Tel:

Cisco Systems, Inc.
7025-6 Kit Creek Road PO Box 14987
RESEARCH TRIANGLE PARK
27709-4987
United States
cisco.com


[http://www.cisco.com/assets/swa/img/thinkbeforeyouprint.gif]Think before you print.

This email may contain confidential and privileged material for the sole use of the intended recipient. Any review, use, distribution or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive for the recipient), please contact the sender by reply email and delete all copies of this message.
Please click here<http://www.cisco.com/web/about/doing_business/legal/cri/index.html> for Company Registration Information.


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