Hi,

On Sat, 9 Oct 2010, Seth Mos wrote:

>> With all drives, the "used surface" starts at the outer corner and does
>> not reach to the inner corner. So 3.5" drives have in any case the bits
>> sliding faster under the heads at a given rpm.
>
> The sequential throughput of the 3.5 inch disk is a lot higher over the 
> 2.5 inch disks.
>
> The smaller platters of the 2.5 inch drives does mean that the end to 
> end swipe of the head is smaller between the 2 formats. This has random 
> seek performance benefits.
>
> The lesser mass of the 2.5 inch platters mean that it normally uses less 
> power as well.
>
> And you can stack a lot more of them into a 2U box == more iops.

Reflecting equal track and bit density, 3.5" needs less tracks due to 
longer circles. So random seek performance benefit too is on the 3.5" 
side.

More iops per physical server volume is the only benefit of 2.5".


Viele Gruesse
Eberhard Moenkeberg ([email protected], [email protected])

-- 
Eberhard Moenkeberg
Arbeitsgruppe IT-Infrastruktur
E-Mail: [email protected]      Tel.: +49 (0)551 201-1551
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