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Message-ID: <867132.21532.qm@web111310.mail.gq1.yahoo.com>
Date: Fri, 10 Dec 2010 11:27:28 -0800 (PST)
From: Andy <angelflow@yahoo.com>
Subject: Re: Hardware recommendations
To: pgsql-performance@postgresql.org,
	Arjen van der Meijden <acmmailing@tweakers.net>
In-Reply-To: <4D026A09.3080108@tweakers.net>
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> The "common knowledge" you based that comment on, may
> actually not be very up-to-date anymore. Current
> consumer-grade SSD's can achieve up to 200MB/sec when
> writing sequentially and they can probably do that a lot
> more consistent than a hard disk.
> 
> Have a look here: http://www.anandtech.com/show/2829/21
> The sequential writes-graphs consistently put several SSD's
> at twice the performance of the VelociRaptor 300GB 10k rpm
> disk and that's a test from over a year old, current SSD's
> have increased in performance, whereas I'm not so sure there
> was much improvement in platter based disks lately?

The sequential IO performance of SSD may be twice faster than HDD, but the random IO performance of SSD is at least an order of magnitude faster. I'd think it'd make more sense to take advantage of SSD's greatest strength, which is random IO.

The same website you linked, anandtech, also benchmarked various configurations of utilizing SSD:  http://www.anandtech.com/show/2739/11

According to their benchmarks putting logs on SSD results in no performance improvements, while putting data on SSD leads to massive improvement. 

They used MySQL for the benchmarks. So perhaps Postgresql is different in this regard?