Subject: Re: Disklabel ioctls (was Re: nore on disk ...)
To: None <tech-kern@NetBSD.ORG>
From: der Mouse <mouse@Collatz.McRCIM.McGill.EDU>
List: tech-kern
Date: 11/21/1995 11:47:17
> I think what bugs me the most is the fact that on some devices,
> notably SCSI, the total size of the disk is often a few to several
> blocks larger than:
> 	sectors/track * tracks/cylinder * cylinders

> Indeed, I have a couple of disk manuals at work that flat out say
> that the disk's reported geometry is _estimated_ based on observed
> averages.

Bingo.  The problem, as I understand it, is that the sectors-per-track
figure varies depending on the cylinder number.  Disk stuff - from the
disklabel to the FFS layout - tends to assume sec-per-trk is fixed.
But It Just Ain't So anymore.  I'm not sure what can be done about it;
I've been toying with some ideas, but they're all very fuzzy as yet.

					der Mouse