Sectors on a hard disk?

[YOyoYOhowsDAjello]

Hey guys. I have a problem for cs-354 that's asking me about sectors on a hard disk

It asks whether there are more sectors per track at the inner track or the outer track on a drive.

I'm thinking that since there's more area on the outer track, it would have more sectors. But it's also moving a lot faster on the outside, so it would be a lot harder for the drive to read a lot of sectors.

I think I'm confusing myself. Could somebody help me out on this one?

 

[Pariah]

More on the outside.

 

[YOyoYOhowsDAjello]

Thanks.

Is the reason just because there's more area? It asked to justify the answer.

 

[Pariah]

Yes, but HD's used something called zone bit recording so you have groups of contiguous tracks with the same number of sectors.

 

[Netopia]

Years ago, mainly when MFM and RLL drives were the norm there was, as you guessed, a problem with drives reading fast enough. The solution to this was to interleave the sectors. In essence, you were PURPOSELY fragmenting your hard drive. Let's say, for instance, that your drive was fast enough to read every third sector... then what you would do would be to initialize your drive for an interleave of 3 and each file would be laid down on every third sector instead of continuous sectors. This made drives MUCH faster because if you missed a sector you'd have to wait for the disk to bring it back around under the heads... and this was on 3600 RPM and slower drives with access times in the three digits.

With today's hard drives you have no such problem. Therefore the old practice of interleaving has gone away and files are written contiguously.... which leads to the answer to your initial question.... the outer surfaces of drives can hold much more data than the inner surfaces. Also, because the inside and the outside travel the same number of RPM's (not true in all CD drives), the outside tracks can have a MUCH higher data transfer rate.

Hope it was helpful,

Joe

 

[YOyoYOhowsDAjello]

Thanks a lot guys.