On Fri, Sep 11, 2009 at 3:20 PM, Eric D. Mudama
<edmud...@bounceswoosh.org>wrote:

> On Fri, Sep 11 at 13:14, Tim Cook wrote:
>
>>  Better IOPS?  Do you have some numbers to back that claim up?  I've never
>>  heard of anyone getting "much better" IOPS out of a drive by simply
>>  changing the interface from SATA to SAS.  Or SATA to FATA for that
>>  matter.  A 7200RPM drive is limited by the 7200RPM's, not the interface
>>  it's attached to.
>>
>
> Depends on the model of drive.
>
> A number of vendors put relatively larger magnets and stronger
> actuators in their enterprise designs, where the customers are willing
> to pay for it.  This can significantly decrease track-to-track seek
> times, which improves IOPS.
>
> On top of that, many enterprise drives are using smaller platters
> and/or higher RPM, both of which also help IOPS at shallow queue
> depths.
>
> At infinitely high queue depth, IOPS basically becomes a function of
> how quickly the servo system can settle, since seek distances approach
> zero (both linearly and rotationally) as the number of operations to
> choose from goes to infinity.
>
>

The question wasn't about consumer vs. enterprise drives.  He said the SAS
interface improves IOPS.  Please don't change the topic of discussion
mid-thread.

--Tim
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