Subject: Re: NetBSD calculates sd geometry oddly?
To: None <netbsd-users@NetBSD.ORG>
From: der Mouse <mouse@Collatz.McRCIM.McGill.EDU>
List: netbsd-users
Date: 05/10/1995 08:07:50
> NetBSD seems to ask the drive for its geometry and multiply values to
> get the total number of sectors on the disk.

IMO this is a very bad idea.  Sun disklabels also work in terms of disk
geometry, which was reasonable in the days when you gave the disk
(cyl,trk,sec) triples, but isn't any longer now that disks act like big
linear arrays of blocks.  Indeed, I now consistently see disks with
variable geometries - the number of sectors per track varies depending
on what the cylinder number is.

I would very much rather see the real size in sectors, if necessary
determined by binary search to see at what point requests fall off the
end of the disk.  (Unfortunately FFS still needs geometry numbers....)

					der Mouse