Gerhard, According to this source, that theory is in question:
http://www.h-online.com/security/Secure-deletion-a-single-overwrite-will -do-it--/news/112432 (watch the wrap). Tom Harper IMS Utilities Development Team Neon Enterprise Software Sugar Land, TX -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Gerhard Postpischil Sent: Thursday, July 02, 2009 4:29 PM To: IBM-MAIN@bama.ua.edu Subject: Re: ERASEDATA - DASD disposal Eric Bielefeld wrote: > I always wondered if it was possible to read data if binary zeros or > some other pattern were written to the disk. I thought that it would be > very hard, which the article quoted seemed to agree with. But then, I > noticed that the writer of the article didn't sign his name. As I understand it, the magnetized portion of a track is slightly wider than the write head. When a track is rewritten, the head alignment will be slightly different, leaving a little bit of the original track. So what you are writing on subsequent passes doesn't really matter, unless you do it often enough to make it unlikely to retain any trace of the original. And of course there are the newfangled storage boxes where you get a different physical track on every write..... Gerhard Postpischil Bradford, VT ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
