How to translate cylinders/heads/sectors to what OpenBSD disklabel wants

[David Benfell <benfell@parts-unknown.org>]

Hello all,

An IDE disk started giving me trouble on my primary server.  So I
decided to replace it (a 15GB disk) and another (6GB) of somewhat
older vintage with a 40GB disk.

These two disks held my root, /usr, and /var partitions, so this means
I need to reinstall OpenBSD.  I have my /home and /public partitions
on another (60GB) disk which remains on the system.

The trouble is that OpenBSD sees only 62MB by default and I'm not
seeing how to get it to see the whole disk.

Linux (via the bootable business card) reports that the drive has 4963
cylinders, 255 heads, and 63 sectors.  The BIOS reports that it has
19541 cylinders, 16 heads, and 255 sectors (and 40GB).

But OpenBSD's disklabel program needs different values and I don't see
how to make the translation.

When I tell disklabel to use the BIOS geometry and recalculate free
space, it reports:

bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16865
cylinders: 1024
total sectors: 16450560
free sectors: 128457

If I understand correctly, this translates to something on the order
of 8GB total.

When I tell it to use the disk geometry, it reports:

bytes/sector: 512
sectors/track: 17
tracks/cylinder: 8
sectors/cylinder: 136
cylinders: 1024
total sectors: 139264
free sectors: 128457

If I understand correctly, this translates to something on the order
of 71MB total.

Disturbingly, it apparently only sees 128457 free sectors even though
the whole disk is supposed to be available for this installation.
That would give me something like 65MB for the installation.
Unsurprisingly, this is not enough.

As this is my mail server, I'm presently unable to receive your
responses at my normal e-mail address.  Please cc me at
benfell@starshine.org

Thank you very much.

--
David Benfell, LCP
benfell@parts-unknown.org
---
Resume available at http://www.parts-unknown.org/resume.html

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