dumb question about fdisk

Martijn van Oosterhout kleptog at svana.org
Fri Aug 23 09:02:17 EST 2002

On Thu, Aug 22, 2002 at 11:58:24PM +1000, Matthew Hawkins wrote:
> Kim Holburn (kim.holburn at anu.edu.au) wrote:
> > I have a disk which is running, mounted etc. and I want to change the
> > bootable flag to another partition.  I change the flag then I have to
> > "write table to disk and exit".  Will this destroy data on my disk?  I
> Yes.  With any luck, it will completely destroy the data containing the
> previous setting of the bootable flag on that partition.


> As for the rest of the disk, in my experience Linux fdisk has never
> touched it.

Actually, there is one case where fdisk will edit other blocks. If you are
making extended partitions then fdisk will use a block to store them. In
fact, when you make multiple extended partitions, the DOS fdisk makes a new
block for each one and chains them. I don't know if the linux fdisk does

The upshot is that if you make lots of extended partitions and delete them,
you may get 512 blocks blatted on the boundaries of where the partitions

Martijn van Oosterhout   <kleptog at svana.org>   http://svana.org/kleptog/
> There are 10 kinds of people in the world, those that can do binary
> arithmetic and those that can't.

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