incremental disk wipe?

[rikona]

Hello Colin,

Saturday, March 7, 2015, 7:01:03 AM, Colin wrote:

> On 7 March 2015 at 06:09, rikona <rikona at sonic.net> wrote:
>> I was checking the timing of securely wiping large disks - looks
>> like it takes a looooong time. Is there a way to do this in smaller
>> 'chunks', that might complete in an hour or so, eventually filling
>> up the entire disk? I'm not hiding plots from NSA, so I don't need
>> extreme security - just enough to discourage easy-tech snoops. :-))

> Use dd with bs, skip and count options to write nulls over selected
> areas. Increasing skip each time.

AIUI [which is not very well :-) ] the concept is to write just a
little each time so it doesn't take very long. I'm a bit confused by
man dd, though, re 'BLOCKS' and increasing skip. Wouldn't I want to
have bs small [512 bytes], vary count over a small range [say 1-5],
have skip start with a good size number [to minimize time] but vary it
up and down a bit on each run to make sure most of the disk is written
to?

Thanks,

-- 

 rikona