SEO

Sorry to blend threads, but in my kinda longish, somewhat thankless,
essentially anonymous, and quite average career as a dba, I have
found that the 7K would be best spent on a definitive end-to-end
"application critical path" test (pretty easy to instrument apps
and lash on test harnesses these days).


If it's "the disk subsystem", then by all means, spend the 7K there.

If the "7K$" is for "hardware only", then disk is always a good choice. For
a really small shop, maybe it's an upgrade to a dual CPU opteron MOBO, eg.
dunno.

If, however, in the far-more-likely case that the application code
or system/business process is the throttle point, it'd be a great
use of money to have a test report showing that to the "higher ups".
That's where the best scalability bang-for-buck can be made.


- Ross

p.s. having said this, and as already been noted "7K" ain't
going to buy that much....maybe the ability to go RAID 10?

p.p.s Why don't we start a PGSQL-7K listserv, to handle this EPIC thread? :-)


-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailtogsql-performance-owner@postgresql.org] On Behalf Of Richard_D_Levine@raytheon.com
Sent: Friday, April 15, 2005 11:20 AM
To: Alex Turner
Cc: Dave Held; pgsql-performance@postgresql.org; pgsql-performance-owner@postgresql.org
Subject: Re: [PERFORM] Intel SRCS16 SATA raid?


This is a different thread that the $7k server thread.
Greg Stark started it and wrote:

"I'm also wondering about whether I'm better off with one of these
SATA raid
controllers or just going with SCSI drives."



Rick

pgsql-performance-owner@postgresql.org wrote on 04/15/2005 10:01:56 AM:

> The original thread was how much can I get for $7k
>
> You can't fit a 15k RPM SCSI solution into $7K Some of us are ona
budget!
>
> 10k RPM SATA drives give acceptable performance at a good price, thats
> really the point here.
>
> I have never really argued that SATA is going to match SCSI
> performance on multidrive arrays for IO/sec. But it's all about the
> benjamins baby. If I told my boss we need $25k for a database
> machine, he'd tell me that was impossible, and I have $5k to do it. If
> I tell him $7k - he will swallow that. We don't _need_ the amazing
> performance of a 15k RPM drive config. Our biggest hit is reads, so
> we can buy 3xSATA machines and load balance. It's all about the
> application, and buying what is appropriate. I don't buy a Corvette
> if all I need is a malibu.
>
> Alex Turner
> netEconomist
>
> On 4/15/05, Dave Held <dave.held@arrayservicesgrp.com> wrote:
> > > -----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
> >
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TIP 8: explain analyze is your friend

Ross,

I agree with you, but I' am the lowly intergrator/analyst, I have to solve the problem without all
the authority (sounds like a project manager). I originally started this thread since I had the $7k budget.

I am not a dba/developer. but I play one on t.v., so I can only assume that throwing money
at the application code means one understand what the bottleneck in the code and what it takes to fix it.

In this situation, the code is hidden by the vendor that connects to the database. So, besides persisent requests of the vendor to improve the area of the application, the balance of tuning lies with the hardware. The answer is *both* hardware and application code. Finding the right balance is key. Your mileage may vary.

Steve Poe




>If, however, in the far-more-likely case that the application code
>or system/business process is the throttle point, it'd be a great
>use of money to have a test report showing that to the "higher ups".
>That's where the best scalability bang-for-buck can be made.


- Ross

>p.s. having said this, and as already been noted "7K" ain't
> going to buy that much....maybe the ability to go RAID 10?

>p.p.s Why don't we start a PGSQL-7K listserv, to handle this EPIC thread? :-)



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