Re: 515 Configuration Funny

[Larry Bolhuis <lbolhuis@xxxxxxxxxx>]

BUT the data is flying under the heads faster at 3.5" than it is at 2.5" 
- 136MPH vs a paltry 47MPH (Pi*R^2*RPM/12/5280*60 ) And yes that's for 
the outside rim. So the 3.5" units are faster. (DON'T Go on about 14" 
platters and S/34 etc.... :-)

But seriously what you don't consider is cost to Design, Manufacture, 
Inventory, and Ship a different form factor of the CEC. Not to mention 
different spare parts to stock around the globe, the drivers and other 
tweaks certain to be required to support such drives, and the fact that 
if they just started shipping there is no way to be sure they will last 
under these conditions.  Am I telling IBM not to consider these drives 
in the future? Don't be silly.  But the current form factor being 
identical to the 520 means economies of scale for all parts of IBM: 
software, hardware, manufacturing, maintenance etc. All of that 
translates to better pricing and reliability for us all.

- Larry



Lukas Beeler wrote:
> 2.5" Drives are usually faster than their 3.5" counterparts at the same
> rotational speed. They have smaller platters.
>
> Also, 16 2.5" drives at 10kRPM will outperform 8 3.5" drives at 15kRPM
> anyway.
>
> -----Original Message-----
> From: midrange-l-bounces@xxxxxxxxxxxx
> [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Jones, John (US)
> Sent: Monday, April 16, 2007 6:19 PM
> To: Midrange Systems Technical Discussion
> Subject: RE: 515 Configuration Funny
>
> There are no 140GB 15K RPM SAS drives.  Seagate is just this month
> shipping their very first 15K 2.5" SAS drives in 36 & 73GB sizes.
> Hitachi doesn't offer 10K RPM 2.5" disks let alone 15K units.
>
> I don't think IBM had much choice in drive formfactor this time around.
>
>