How to delete all partitions for a complete reinstall

[Tony Arnold]

On Tue, 2006-08-15 at 15:31 +0200, Alexander Skwar wrote:
> Tony Arnold <tony.arnold at manchester.ac.uk>:

> >> With Erics command, a "huge" number of write requests is sent (512,
> >> to be exact). And every time, just 1 byte is written. That's tremendously
> >> slow!
> > 
> > And possible 512 reads too, as for each byte written, dd would have to
> > read the block first before writing it back again.
> 
> True.
> 
> > It could cache the 
> > block, of course.
> 
> Caching the 1 byte read from /dev/zero? :)

No, I mean to update a single byte on a block on the disk, the block has
to be read first, the byte added and then the block written back. If dd
knows it already has a copy of the block it could optimize out
subsequent reads.

> > zzalsaca at beeblebrox:~$ time dd if=/dev/zero of=zero.bs2    bs=
> > $((1*1024*1024)) count=1
> > 1+0 records in
> > 1+0 records out
> > Segmentation fault
> > 
> > real    0m0.035s
> > user    0m0.000s
> > sys     0m0.020s
> > zzalsaca at beeblebrox:~$ ls -l zero.bs*
> > -rw-r--r-- 1 zzalsaca zzalsaca 1048576 2006-08-15 13:39 zero.bs1
> > -rw-r--r-- 1 zzalsaca zzalsaca 1048576 2006-08-15 13:40 zero.bs2
> > 
> > But I also get a segmentation fault in the middle of dd's output.
> 
> In the middle? According to your output, the dd was complete.

Sorry, it was at the end of dd's output and before time output it's
stuff. On another machine dd prints out a summary and data rate
information.

> > Is 
> > this due to running the -26 kernel? or something else?
> 
> I don't know.

Must be to do with my laptop, as another machine running the latest
kernel did not give segmentation fault. Weird.

Regards,
Tony.
-- 
Tony Arnold, IT Security Coordinator, University of Manchester,
IT Services Division, Kilburn Building, Oxford Road, Manchester M13 9PL.
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E: tony.arnold at manchester.ac.uk, H: http://www.man.ac.uk/Tony.Arnold