NOTE: If you wish to install OpenBSD on your whole disk, i.e. you do
not want DOS or any other operating system to reside on your hard
disk, you can skip this section and go on to the section that
describes installation, below.  If you're upgrading your system from a
previous release of OpenBSD, you should have proceeded directly to the
section about upgrading; you need none of the information presented
here.

First and foremost, before beginning the installation process, MAKE
SURE YOU HAVE A RELIABLE BACKUP of any data on your hard disk that you
wish to keep.  Repartitioning your hard disk is an excellent way to
destroy important data.

Second, if you are using a disk controller which supports disk geometry
translation, be sure to use the same parameters for OpenBSD as for DOS
or the other operating systems installed on your disk.  If you do not,
it will be much harder to make OpenBSD properly coexist with them.
Utilities exist which will print out the disk geometry which DOS sees;
some versions of DOS "fdisk" also do this.  If you have an "EIDE" hard
disk, DOS and OpenBSD probably won't see the same geometry, and you must
be careful to find out the DOS geometry and tell OpenBSD about it during
the installation.

Third (but related to the second point above), if you are using a hard
disk with more sectors than DOS or your controller's BIOS supports without
some kind of software translation utility or other kludge, you MUST
BE SURE that all partitions which you want to boot from must start and end
below cylinder 1024 by the BIOS's idea of the disk, and that all DOS
partitions MUST EXIST ENTIRELY BELOW cylinder 1024, or you will either not
be able to boot OpenBSD, not be able to boot DOS, or you may experience
data loss or filesystem corruption.  Be sure you aren't using geometry
translation that you don't know about, but that the DOS "fdisk" program
does!

The OpenBSD root partition must also reside completely within the BIOS
supported part of the hard disk -- this would typically be 504M, 2G or 8G,
depending upon the age of the machine and its BIOS.  Due to a limit of the
OpenBSD boot loader, the root partition must be within the first 8G even if
the BIOS supports more.  Note that only the root partition has this issue,
once OpenBSD is loaded, the entire disk is available for use.

Fourth, use the other operating system's "fdisk" program or partition
editor to create at least one of the partitions to be used for that
operating system.  If that operating system is already set up to use the
entire disk, you will have to back it up, remove and recreate a smaller
partition for it, and then restore the data from that partition.  You do
not have to create an OpenBSD partition at this time, the OpenBSD install-
ation will give you an opportunity to create the partition needed for
OpenBSD.

Finally, do whatever is necessary to restore order to the partition
you took space away from.  If it was a DOS partition, you probably
will need to use "format" to create a new file system on it, and then
restore your important files from your backups.  Other operating
systems will have different needs; most will need to reformat the
partition, and if it was their "main" partition, will probably need
to be reinstalled.

Once you've backed all your data up, there is a tool called fips 2.0
that can shrink your FAT-based DOS/Windows partition to make room for
OpenBSD.  It is included in the MACHINE tools area of this distribution as
a convenience.  It is strongly advised that you read its documentation
and understand the consequences of your actions before using it.  In some
cases, defragmenting your disk and running fips may be much faster than
reinstalling your DOS partition from the backup.

Your hard disk is now prepared to have OpenBSD installed on it, and
you should proceed with the installation instructions.