How to delete all partitions for a complete reinstall

[Alexander Skwar]

Gary W. Swearingen <garys at opusnet.com>:

> Alexander Skwar <listen at alexander.skwar.name> writes:
> 
>> 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!
> 
> I'm not so sure.

Then test it :)

[16:47:56 vz6tml at dewup-ww02:/neu/opt/tmp] $ time dd if=/dev/zero of=zero.bs1    count=$((1*1024*1024)) bs=1
1048576+0 Datensätze ein
1048576+0 Datensätze aus
1048576 Bytes (1,0 MB) kopiert, 2,22787 Sekunden, 471 kB/s

real    0m2.231s
user    0m0.207s
sys     0m2.020s
[16:48:01 vz6tml at dewup-ww02:/neu/opt/tmp] $ time dd if=/dev/zero of=zero.bs512    count=$(((1*1024*1024)/512)) bs=512
2048+0 Datensätze ein
2048+0 Datensätze aus
1048576 Bytes (1,0 MB) kopiert, 0,007325 Sekunden, 143 MB/s

real    0m0.011s
user    0m0.003s
sys     0m0.007s

As you can see, dd with bs=1 took 2.231s. With bs=512, it took 0.011s.

> "dd" complains or pads or what.  But I very much doubt if it reads,
> changes a byte, and writes back.

I would think so. IIRC, it'll flush after every bs. This will mean, that
the 1 byte will be written to disk.

Alexander Skwar
-- 
Westheimer's Discovery:
        A couple of months in the laboratory can frequently save a
        couple of hours in the library.