[CentOS] erase disk

[John R Pierce]

On 9/27/2013 7:05 AM, m.roth at 5-cent.us wrote:
>> At a former place of employment we would simply not leave hard drives in
>> >servers or desktops that were intended to be recycled or junked.  The hard
>> >drives got disposed of separately (in this case crushed with a hydraulic
>> >wedge).
> Hah! When we have one that's failed, it gets deGaussed here. (Except for
> old, 1.5x height SCSI drives, for which they "don't have a frame". Then we
> unscrew the thing, and disassemble, and have cool magnets, and pretty
> disks (which we can bend, or hit with a hammer).

ours are collected in a secure area, then once a month or so a chipper 
truck comes by and grinds them up to dust.

my feelings on disk erasure, based on years and years of being ni this 
industry (I started programming in 1973 with FORTRAN and punchcards, and 
worked on disk device drivers in the late 70s, early 80s, and work for a 
storage company now these last 15 years).

DOD xxxxwhatever is obsolete and meaningless.   its not even used by the 
DOD anymore, they physically destroy anything secret.  to reasonably 
safely erase an modern disk (thats anything since MFM/ESDI became 
obsolete), one pass of anything (1's is fine) and one pass of zeros is 
more than sufficient... EXCEPT modern disks have automatic bad block 
remapping, and its /very/ possible for there to still be readable albeit 
old data on those bad blocks. if that possibility of data leakage is 
unacceptable, physical destruction is appropriate.

-- 
john r pierce                                      37N 122W
somewhere on the middle of the left coast