Importance of Number of Platters?

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Nagarya

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Jun 8, 2012
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I'm currently looking for a 2 TB HDD for my first build, and the cheapest one I found with 7200 RPM was the Seagate Barracuda ST2000DM001. (I was only looking at Seagate and Western Digital since people were saying they're usually the best quality)

http://www.amazon.com/dp/B005T3GRN2/?tag=pcpapi-20

However, when I was reading the reviews on Amazon, I noticed the Most Helpful review was a 1-Star mentioning that it was basically a toss-up whether you'd receive a 2-platter or 3-platter HDD, and that more platters means less performance and greater chance of early failure.

I wanted to ask, how big a difference is it? Should I try and look for something that is guaranteed to be 2-platter, and if so, how expensive are they usually? (I wouldn't mind having recommendations :) )
 
Solution
JackNaylorPE


People say these things based upon anectdotal experience. Most don't have a substantial enough sample size to be able to make a qualified judgement. But look at sites like storagreview.com What I find is that every brand has its share of great drives and bombs. You'll note at that site, Seagate has both the best drive and the worse drive in the reliability charts. You'll also note how poorly the otherwise well regarded Raptor series does.

As you your question....with drives of the same size and rpm, less platters is better.

A 2TB drive with 2 platter has 1 platter per TB
A 2TB drive with 4 platter has 1 platter...
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JackNaylorPE

JackNaylorPE

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Oct 30, 2004
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People say these things based upon anectdotal experience. Most don't have a substantial enough sample size to be able to make a qualified judgement. But look at sites like storagreview.com What I find is that every brand has its share of great drives and bombs. You'll note at that site, Seagate has both the best drive and the worse drive in the reliability charts. You'll also note how poorly the otherwise well regarded Raptor series does.

As you your question....with drives of the same size and rpm, less platters is better.

A 2TB drive with 2 platter has 1 platter per TB
A 2TB drive with 4 platter has 1 platter per half TB

That means the 2 platter drive has twice the aereal density and therefore at the same rpm, will read twice as much info as the 4 platter drive and therefore is twice as fast in sequential reads.

 
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F

fzabkar

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Sep 22, 2010
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"That means the 2 platter drive has twice the aereal density and therefore at the same rpm, will read twice as much info as the 4 platter drive and therefore is twice as fast in sequential reads."

In fact the data transfer rate is related to the linear density, not areal density. Therefore the 4-platter drive will have a transfer rate that is lower by a factor of sqrt(2), ie 71%.

In the case of the 3-platter versus the 2-platter drive, the ratio of transfer rates would be ...

sqrt(2 / 3) = 82%
 
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