Message-ID: <519D2562.2060604@2ndQuadrant.com>
Date: Wed, 22 May 2013 16:06:58 -0400
From: Greg Smith <greg@2ndQuadrant.com>
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To: Merlin Moncure <mmoncure@gmail.com>
CC: "Joshua D. Drake" <jd@commandprompt.com>, sthomas@optionshouse.com,
	Tomas Vondra <tv@fuzzy.cz>, pgsql-performance@postgresql.org
Subject: Re: Reliability with RAID 10 SSD and Streaming Replication
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On 5/22/13 3:51 PM, Merlin Moncure wrote:
> s3700 is rated for 10 drive writes/day for 5 years. so, for 200gb drive, that's
> 200gb * 10/day * 365 days * 5, that's 3.65 million gigabytes or ~ 3.5 petabytes.

Yes, they've improved on the 1.5PB that the 710 drives topped out at. 
For that particular drive, this is unlikely to be a problem.  But I'm 
not willing to toss out longevity issues at therefore irrelevant in all 
cases.  Some flash still costs a lot more than Intel's SSDs do, like the 
FusionIO products.  Chop even a few percent of the wear out of the price 
tag on a RAMSAN and you've saved some real money.

And there are some other products with interesting 
price/performance/capacity combinations that are also sensitive to 
wearout.  Seagate's hybrid drives have turned interesting now that they 
cache writes safely for example.  There's no cheaper way to get 1TB with 
flash write speeds for small commits than that drive right now.  (Test 
results on that drive coming soon, along with my full DC S3700 review)

> btw,  cost/pb of this drive is less than half of
> the 710 (which IMO was obsolete the day the s3700 hit the street).

You bet, and I haven't recommended anyone buy a 710 since the 
announcement.  However, "hit the street" is still an issue.  No one has 
been able to keep DC S3700 drives in stock very well yet.  It took me 
three tries through Newegg before my S3700 drive actually shipped.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com


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