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Date: Fri, 03 Apr 2009 21:53:12 +1300
From: Mark Kirkwood <markir@paradise.net.nz>
Subject: Re: Raid 10 chunksize
In-reply-to: <49D321C1.1000405@paradise.net.nz>
To: Scott Carey <scott@richrelevance.com>
Cc: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
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Mark Kirkwood wrote:
> Rebuilt with 256K chunksize:
>
> transaction type: TPC-B (sort of)
> scaling factor: 100
> number of clients: 24
> number of transactions per client: 12000
> number of transactions actually processed: 288000/288000
> tps = 942.852104 (including connections establishing)
> tps = 943.019223 (excluding connections establishing)
>

Increasing checkpoint_segments to 96 and decreasing 
bgwriter_lru_maxpages to 100:

transaction type: TPC-B (sort of)
scaling factor: 100
number of clients: 24
number of transactions per client: 12000
number of transactions actually processed: 288000/288000
tps = 1219.221721 (including connections establishing)
tps = 1219.501150 (excluding connections establishing)

... as suggested by Greg (actually he suggested reducing 
bgwriter_lru_maxpages to 0, but this seemed to be no better). Anyway, 
seeing quite a reasonable improvement (about 83% from where we started). 
It will be interesting to see how/if the improvements measured in 
pgbench translate into the "real" application. Thanks for all your help 
(particularly to both Scotts, Greg and Stef).

regards

Mark