sysinstall: label editor:unable to write data

Björn König bkoenig at
Fri Jun 17 11:45:48 GMT 2005

Per olof Ljungmark wrote:
> I am trying to modify the da0s1 slices on a harddisk under 5.4 using 
> /usr/sbin/sysinstall.
> I delete an existing slice and create two new ones in the old freed 
> space. When writing the changes I get:
> ERROR: Unable to write data to disk da0!

Partitions (slices) will be written to the first sector of the hard disk 
which is called the MBR as you probably know. FreeBSD has a mechanism to 
prevent that you overwrite, change or destroy your MBR accidentally. You 
need to run

   sysctl kern.geom.debugflags=16

to deactivate this mechanism temprorarily. Another way would be to boot 
from a Live CD, e.g. disc1 (disc2 for 5.3 and older) and then make the 


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