Hitchhiker's Guide to Openbsd

4.6.3 - Custom fdisk(8) layout
Note: only some OpenBSD platforms use fdisk at all, and usually, only 
i386
 and 
amd64
 users will have to worry about 
getting fancy with fdisk. Users of most other fdisk(8) using platforms generally don't have to worry about multibooting or 
setup/diagnostic partitions. For this reason, this section is focused on i386 and amd64. 
fdisk(8)
 is used to mark off the OpenBSD part of your hard disk. It helps mark off the part of the disk used by OpenBSD 
from the parts used by other OSs or system functions. 
If you have a partition on your disk you wish to retain or wish to leave space for another partition, you will NOT want to 
chose "(W)hole disk", but will need to edit the partition table with 
fdisk(8)
. More information on manually running fdisk
(8) can be found 
here
. Before working with any system that has data you don't wish to lose, make sure you have a 
good backup. It is very easy in this process to clobber important data, so make sure you are ready to get it back, if need 
be. 
If you are adding OpenBSD to an existing system, you will probably need to create some free space on your system 
before installing OpenBSD. This will usually involve deleting or possibly reducing the size of existing partitions. The 
program 
gparted
 has been found useful for shrinking the partitions of many popular OSs, making it possible to install 
OpenBSD on the freed space. 
In this example, we will assume we are starting with a blank 40G disk and wish to create a multi-boot system, reserving 
5G at the beginning of the disk for Windows, and the rest for OpenBSD. Note that a blank drive has to have valid MBR 
boot code and signature written to the disk before it can be booted. 
The process is very much the same for working around an existing partition, you just need to skip over the parts where 
we create the Windows partition and worry about installing the MBR boot code. 
Available disks are: wd0.
Which one is the root disk? (or 'done') [wd0] Enter
MBR has invalid signature; not showing it.
IF the disk had a valid MBR in place, it would show you the existing partition table, which can be a good way to show if 
a disk may have data on it already. 
http://www.openbsd.org/faq/faq4.html (18 of 43)9/4/2011 10:01:58 AM

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4 - OpenBSD 4.9 Installation Guide
Use (W)hole disk or (E)dit the MBR? [whole] e
You will now create a single MBR partition to contain your OpenBSD data. This