Message-ID: <4C63A12B.7050607@tweakers.net>
Date: Thu, 12 Aug 2010 09:22:19 +0200
From: Arjen van der Meijden <acmmailing@tweakers.net>
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To: pgsql-performance@postgresql.org
Subject: Re: Completely un-tuned Postgresql benchmark results: SSD
	vs desktop HDD
References: <20100811205356.AHB77050@ms14.lnh.mail.rcn.net>
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On 12-8-2010 2:53 gnuoytr@rcn.com wrote:
> - The value of SSD in the database world is not as A Faster HDD(tm).
> Never was, despite the naive' who assert otherwise.  The value of SSD
> is to enable BCNF datastores.  Period.  If you're not going to do
> that, don't bother.  Silicon storage will never reach equivalent
> volumetric density, ever.  SSD will never be useful in the byte bloat
> world of xml and other flat file datastores (resident in databases or
> not).  Industrial strength SSD will always be more expensive/GB, and
> likely by a lot.  (Re)factoring to high normalization strips out an
> order of magnitude of byte bloat, increases native data integrity by
> as much, reduces much of the redundant code, and puts the ACID where
> it belongs.  All good things, but not effortless.

It is actually quite common to under-utilize (short stroke) hard drives 
in the enterprise world. Simply because 'they' need more IOps per amount 
of data than a completely utilized disk can offer.
As such the expense/GB can be much higher than simply dividing the 
capacity by its price (and if you're looking at fiber channel disks, 
that price is quite high already). And than it is relatively easy to 
find enterprise SSD's with better pricing for the whole system as soon 
as the IOps are more important than the capacity.

So in the current market, you may already be better off, price-wise, 
with (expensive) SSD if you need IOps rather than huge amounts of 
storage. And while you're in both cases not comparing separate disks to 
SSD, you're replacing a 'disk based storage system' with a '(flash) 
memory based storage system' and it basically becomes 'A Faster HDD' ;)
But you're right, that for data-heavy applications, completely replacing 
HDD's with some form of SSD is not going to happen soon, maybe never.

Best regards,

Arjen