Message-ID: <4C637D42.5040208@2ndquadrant.com>
Date: Thu, 12 Aug 2010 00:49:06 -0400
From: Greg Smith <greg@2ndquadrant.com>
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To: gnuoytr@rcn.com
CC: 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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gnuoytr@rcn.com wrote:
> Sufficiently bulletproof flash SSD exist and have for years, but their names are not well known (no one on this thread has named any)

The models perceived as bulletproof are the really dangerous ones to 
deploy.  First, people let their guard down and stop being as paranoid 
as they should be when they use them.  Second, it becomes much more 
difficult for them to justify buying more than one of the uber-SSD.  
That combination makes it easier to go back to having a single copy of 
their data, and there's a really bad road to wander down.

The whole idea that kicked off this thread was to enable building 
systems cheap enough to allow making more inexpensive copies of the 
data.  My systems at home for example follow this model to some degree.  
There's not a single drive more expensive than $100 to be found here, 
but everything important to me is sitting on four of them in two systems 
within seconds after I save it.  However, even here I've found it worth 
dropping enough money for a real battery-backed write cache, to reduce 
the odds of write corruption on the more important of the servers.  Not 
doing so would be a dangerously cheap decision.  That's similar to how I 
feel about SSDs right now too.  You need them to be expensive enough 
that corruption is unusual rather than expected after a crash--it's 
ridiculous to not spend enough to get something that's not completely 
broken by design--while not spending so much that you can't afford to 
deploy many of them. 

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us