Re: Trouble with 3GB EIDE drive

[Tobias Weingartner <weingart@wolfram.com>]

On Monday, July 6, Dan Grabski wrote:
> I'm trying to install OpenBSD on a Intel Pentium 200MMX system
> with a Western Digital Caviar 33200 drive (3249MB, 6296 cylinders,
> 16 heads, 63 sec/track). My BIOS sees the drive fine, and when
> I boot from the installation floppy (I'm going to install from
> a CD), the initial messages say that it found the hard drive
> at wd0, with all 6296 cylinders, 16 heads, and 3GB of space.

Those are the PHYSICAL numbers for your drive.


> Now the problem -- I try to partition about 450MB for the root
> and swap partition, so I can stay below the 1024th cylinder.

Chances are your system TRANSLATES the physical numbers into a
logical (of sorts) geometry, which you should use with fdisk.

The current boot/kernel/fdisk should already have those numbers
for you to use.  The fact that there are 6000+ physical cylinders
means nothing for 1024 translated cylinders.


> So I partition that in fdisk, but it then refuses to see
> any of the hard drive above about 512MB. I want to use all 3GB
> of the drive for OpenBSD.

What was your geometry as reported by fdisk?


> So what am I missing? I've been looking through manpages and readmes
> trying to find the answer, but I haven't had any luck. Thanks
> for any help you can provide.

The following should be true on 90+% of current machines out there.  Tell
fdisk where you want the partition to start.  (The default is likely ok)
And how big you want it to be (don't worry about the 1024 limit), and
chances are that you will be fine.

Look:

natasha:1065> dmesg | grep sd0
sd0 at scsibus0 targ 0 lun 0: <SEAGATE, ST34572N, 0784> SCSI2 0/direct fixed
sd0: 4340MB, 6300 cyl, 8 head, 176 sec, 512 bytes/sec, 8888924 sec total

natasha:1066> fdisk sd0
Disk: sd0       geometry: 553/255/63 [8883945 sectors]

As you can see, the BIOS maps the 6300 cylinders into something less than 1023.

--Toby.