Subject: Re: disk discrepancies
To: Ray Phillips <>
From: Jochen Kunz <>
List: port-alpha
Date: 02/24/2005 10:53:17
On Thu, 24 Feb 2005 16:50:30 +1000
Ray Phillips <> wrote:

> more surprised to see it has fewer sectors than the other=20
> ST15150N's even though it has the same number of cylinders, heads and=20
> sectors.
"Modern" disks use ZBR, Zone Bit Recording. As the outer tracks of a
disk are larger due to the larger diameter of the track there is more
room for more bits on this longer tracks. So the outer tracks are
formated with more sectors per track as the inner tracks. I.e. The C/H/S
geometry is not constant over the entire disk. Therefore you can't
specify a real C/H/S mapping for this disks. The C/H/S mapping they tell
you is only a fake to make old software, that still needs it, happy.
Especially SCSI disks are just LBA addressed, not C/H/S.

It isn't that uncommon that disks of the same typecode have slight
differences in size due to different hardware or firmware revisions.