[ale] A little math

[Greg Freemyer]

On Wed, Feb 10, 2010 at 12:54 PM, Brian Pitts <brian at polibyte.com> wrote:
> On 02/10/2010 11:35 AM, Scott Castaline wrote:
>> Okay I've got a dumb question for you math types. How long should it
>> take to fill a 1TB hdd with random data using
>> "dd if=/dev/urandom of=/dev/sd"? I've done some more searching and found
>> some numbers and if I figured them right I'm looking at about 8 days. Is
>> this accurate?
>
> That sounds in the ballpark for me.
>
> We do a one pass wipe with random data on hard drives donated to Free IT
> Athens. Even though most of our drives are 10 or 20 GB, on old computer
> systems it takes hours. It doubles as a great stress test though.
>

NIST has a media sanitation guideline.

For drive 20GB or larger a single pass with zeros is sufficient per
that guideline.  They reference a NSA study on laboratory based data
recovery showing this is sufficient.  Unfortunately I've never been
able to get my hands on the NSA paper.

My 64-bit linux boxes can wipe with zeros at about 5GB/min.

Or 300 GB/hr.  So 3 hrs for a 1TB.   Maybe twice that long if your
using a 6 or 7 yr old machine. (ie. 6 hrs).

Greg