From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,1101264a9f24d62d X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!newshub.sdsu.edu!elnk-nf2-pas!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread3.news.pas.earthlink.net.POSTED!a6202946!not-for-mail From: Jeffrey Carter Organization: jrcarter commercial-at acm [period | full stop] org User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Wiping a disk clean References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Date: Wed, 03 Aug 2005 03:28:47 GMT NNTP-Posting-Host: 4.240.111.116 X-Complaints-To: abuse@earthlink.net X-Trace: newsread3.news.pas.earthlink.net 1123039727 4.240.111.116 (Tue, 02 Aug 2005 20:28:47 PDT) NNTP-Posting-Date: Tue, 02 Aug 2005 20:28:47 PDT Xref: g2news1.google.com comp.lang.ada:3918 Date: 2005-08-03T03:28:47+00:00 List-Id: Larry Hazel wrote: > If I create a binary file, use sequential_io to write records of all > ones until Use_Error is raised. Then, delete the file and repeat with > all zeros. > Will the unused portion of the disk be wiped clean so that no one could > recover what was written there before? Probably not. The US Govt requires 3 passes with specific patterns, and the most exhaustive study of the issue indicates that different approaches are required for different kinds of drives. For most modern disks, several passes with random data will suffice. "Several" is probably 5 or 6. And that doesn't even get into the issues of whether Sequential_IO will write on all the unused portion of the disk, much less the unused parts of partially used sectors, and so on. -- Jeff Carter "You couldn't catch clap in a brothel, silly English K...niggets." Monty Python & the Holy Grail 19