Message-ID: <4DE618D7.7000102@2ndquadrant.com>
Date: Wed, 01 Jun 2011 06:47:51 -0400
From: Greg Smith <greg@2ndquadrant.com>
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To: Ray Stell <stellr@cns.vt.edu>
CC: pgsql-admin@postgresql.org
Subject: Re: patching the OS of a 9.0.4 db with hot standby
References: <20110519134009.GA16689@cns.vt.edu>
In-Reply-To: <20110519134009.GA16689@cns.vt.edu>
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Ray Stell wrote:
> I want to do OS patching on prod and hot standby.  What is the advised
> procedure for maintenance on the two systems?  I would think patching
> the standby should come first in case it blows something up. Oracle has
> a defer switch you can throw on prod to tell it to relax on log shipping
> to the standby.  Do we have that here?
>   

Your intuition here is reasonable--test on the standby, if things go 
wrong consider reversing the patch, with no impact on the master.  It's 
not covered in the main because that tends not to cross over into OS 
management considerations.

The main parameter you could consider tweaking in this case is 
wal_keep_segments, which will let you adjust how long the master queues 
things for the standby before it gives up.  If you really do lose the 
standby, you can run out of disk space on the master eventually if you 
haven't set this properly.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books