From: Greg Smith <greg@2ndquadrant.com>
To: Brad Nicholson <bnichols@ca.afilias.info>
Cc: Thomas Kellerer <spam_eater@gmx.net>
Cc: pgsql-admin@postgresql.org
Subject: Re: High Availability: Hot Standby vs. Warm Standby
Date: Mon, 12 Jul 2010 12:16:40 -0400
Message-ID: <4C3B3FE8.1030409@2ndquadrant.com> (raw)
In-Reply-To: <1278941155.29426.44.camel@bnicholson-desktop>
References: <i172f8$kug$1@dough.gmane.org>
<4C386B33.8090708@2ndquadrant.com>
<i1eefg$je9$1@dough.gmane.org>
<1278941155.29426.44.camel@bnicholson-desktop>
Brad Nicholson wrote:
> One further thing to mention - all of these solutions are based on
> making the physical blocks available (actually, I'm not sure about
> Streaming replication in 9.0).
You're right here; the SR feature in 9.0 is essentially near real-time
partial WAL file shipping, and the WAL contains physical disk block
change data. If your master has data blocks corrupted, the next time
you do a base backup against it that corruption will be mirrored to the
standby too. I've mentioned on one of these lists recently that I like
to schedule a periodic pg_dump even if log shipping is the main backup
mechanism for a database, just so that corruption in the underlying
files is caught as early as possible by trying to read every block and
confirm it has valid data.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com www.2ndQuadrant.us
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To: pgsql-admin@postgresql.org
Cc: greg@2ndquadrant.com, bnichols@ca.afilias.info, spam_eater@gmx.net
Subject: Re: High Availability: Hot Standby vs. Warm Standby
In-Reply-To: <4C3B3FE8.1030409@2ndquadrant.com>
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