FreeBSD fdisk/sysinstall

Jerry McAllister jerrymc at
Sat Aug 9 16:48:54 PDT 2003

> I tried to invoke sysinstall to write an additional FreeBSD slice
> to the disk I was currently booted from.
> I intentionally chose the W option to write the changes since
> I didn't want to do an installtion. But I got an error that I could
> not write to the disk.
> Why is that? Because I'm booted from that disk? 


>                            Don't know. Just wondering.
> Is there a neat fdisk for FreeBSD like the linux fdisk
> (which is pfdisk derived, I believe). The FreeBSD fdisk
> is really archaic and I was not able to specify start/end
> block numbers. The calulated cyl numbers seemed to overlap
> with the previous partition so I bailed out and left
> it as it was and put up this question instead.

You do not want to calculate block numbers in any old way when
you make slices, just offset and size..   You do that a little 
when you do disklabel.  The cylinder, track, sector values are 
virtual on mondern disks and do not map directly to the disk's 
actual cylinders, tracks and sectors - at least for SCSI drives 
and so you don't want to mess with them.   Let the system (fdisk 
and the disk controller) deal with them.


> --
> Chris Christoph P. U. Kukulies kukulies (at)

More information about the freebsd-questions mailing list