[Ti] Toshiba's New 100GB 2.5-inch HDD

[Dr. Trevor J. Hutley]

At 12:10 -0500 23/4/04, Kynan Shook wrote:
>Two notes:
>First, it would certainly be *possible* to add another platter, but 
>I doubt Toshiba would do it.  If you look at their 2.5" drives, all 
>of them are 9.5 mm tall.  And, since it seems to me like Toshiba has 
>been the one recently with the largest laptop drives, I'm not sure 
>anybody else will beat them, either.  Additionally, all of Apple's 
>current laptops are limited to 9.5 mm height drives; I'm going to 
>bet that 12 mm drives are quickly going the way of the 15 and 19 mm 
>ones (or something like those sizes, might not be exactly right).
>
>
>Also, as far as rotational speed versus size, you're missing one 
>thing: there are 4 surfaces in both the 80 and 100 GB drives (both 
>sides of 2 platters), and the size of the platters are the same. 
>Hence the areal density is much higher (as they mention in the 
>article) - likely about 25% higher.  Now, certainly some of that 
>added density will be added by putting more cylinders in the drive 
>(eg increasing the radial linear density), but some of that added 
>density is also added along the direction of motion; I'd say angular 
>density, but that wouldn't be right (the angular density depends on 
>the radius); so it's really just linear density along a particular 
>arc that is being increased.  Anyway,  you're getting a drive that 
>spins 23% slower, but bits are flying under the head almost as fast 
>as a lower-density 5400 RPM drive.
>
>The bottom line is this: if you really want speed, you shouldn't be 
>using a laptop to begin with.  Go buy a G5.  If you want storage 
>space, the 100 GB drive will probably be close to the same speed as 
>the 5400 RPM 80 GB drive (and faster than the 4200 RPM 80 GB drive). 
>If you don't want either, stick with what you've got.  If you want 
>both, can I interest you in an Xserve RAID?


I am so glad we have a real technical guy keeping out thinking 
straight and clear.
Kynan, these points you made are a very good contribution to the 
Powerbook University knowledge base.
Without this sort of input, our thinking would get woolly.

Trevor