Re: Rather large LA - Mailing list pgsql-performance

From Scott Marlowe
Subject Re: Rather large LA
Date
Msg-id CAOR=d=2WjEiFhbAL4f7EZi38ZeDSexdnhD_EEcgsPd8A8fwc7w@mail.gmail.com
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In response to Re: Rather large LA  (Andres Freund <andres@anarazel.de>)
Responses Re: Rather large LA
List pgsql-performance
On Mon, Sep 5, 2011 at 11:24 AM, Andres Freund <andres@anarazel.de> wrote:
> On Monday, September 05, 2011 14:57:43 Richard Shaw wrote:
>> Autovacuum has been disabled and set to run manually via cron during a quiet
>> period and fsync has recently been turned off to gauge any real world
>> performance increase, there is battery backup on the raid card providing
>> some level of resilience.
> That doesn't help you against a failure due to fsync() off as the BBU can only
> protect data that actually has been written to disk. Without fsync=on no
> guarantee about that exists.

Further, if you've got a bbu cache on the RAID card the gains from
fsync=off wll be low / nonexistent.

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