Re: Intel SRCS16 SATA raid?

> -----Original Message-----
> From: Alex Turner [mailto:armtuk@gmail.com]
> Sent: Thursday, April 14, 2005 6:15 PM
> To: Dave Held
> Cc: pgsql-performance@postgresql.org
> Subject: Re: [PERFORM] Intel SRCS16 SATA raid?
>
> Looking at the numbers, the raptor with TCQ enabled was close or
> beat the Atlas III 10k drive on most benchmarks.

And I would be willing to bet that the Atlas 10k is not using the
same generation of technology as the Raptors.

> Naturaly a 15k drive is going to be faster in many areas, but it
> is also much more expensive.  It was only 44% better on the server
> tests than the raptor with TCQ, but it costs nearly 300% more ($538
> cdw.com, $180 newegg.com).

State that in terms of cars.  Would you be willing to pay 300% more
for a car that is 44% faster than your competitor's?  Of course you
would, because we all recognize that the cost of speed/performance
does not scale linearly.  Naturally, you buy the best speed that you
can afford, but when it comes to hard drives, the only major feature
whose price tends to scale anywhere close to linearly is capacity.

> Note also that the 15k drive was the only drive that kept up with
> the raptor on raw transfer speed, which is going to matter for WAL.

So get a Raptor for your WAL partition. ;)

> [...]
> The Raptor drives can be had for as little as $180/ea, which is
> quite a good price point considering they can keep up with their
> SCSI 10k RPM counterparts on almost all tests with NCQ enabled
> (Note that 3ware controllers _don't_ support NCQ, although they
> claim their HBA based queueing is 95% as good as NCQ on the drive).

Just keep in mind the points made by the Seagate article.  You're
buying much more than just performance for that $500+.  You're also
buying vibrational tolerance, high MTBF, better internal
environmental controls, and a pretty significant margin on seek time,
which is probably your most important feature for disks storing tables.
An interesting test would be to stick several drives in a cabinet and
graph how performance is affected at the different price points/
technologies/number of drives.

__
David B. Held
Software Engineer/Array Services Group
200 14th Ave. East,  Sartell, MN 56377
320.534.3637 320.253.7800 800.752.8129