On Sun, Dec 02, 2001 at 08:03:58PM +0100, Gilles Gravier wrote:
> Hi!
> 
> So my disk says:
> 
> 8188 cyl, 3 head, 172 sect, 512 bytes/sect x 4226725 sectors
> 
> So that translates in:
> 
> bytes/sector: 512
> sectors/track: 172
> tracks/cylinder: 3
> sectors/cylinder: 516 # 3 * 172
> cylinders: 8188
> total sectors: 4226725
> 
> Right?
> 
> But 8188*516=4225008 sectors... when the disk says 4226725 ?
> 
> Am I missing something?

Modern disks are fixed density, so the number of sectors per track is variable
(depends on the head positions). The reported geometry is only an average
value, and the total number of sectors doesn't match the geometry.
This isn't a problem as we address the drive with a LBA, not a CHS address.

--
Manuel Bouyer <bouyer@antioche.eu.org>
--