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!news.glorb.com!wns13feed!worldnet.att.net!209.244.4.230!newsfeed1.dallas1.level3.net!news.level3.com!news.binc.net!kilgallen From: Kilgallen@SpamCop.net (Larry Kilgallen) Newsgroups: comp.lang.ada Subject: Re: Wiping a disk clean Date: 2 Aug 2005 23:30:23 -0500 Organization: LJK Software Message-ID: References: NNTP-Posting-Host: eisner.encompasserve.org X-Trace: grandcanyon.binc.net 1123043378 14792 192.135.80.34 (3 Aug 2005 04:29:38 GMT) X-Complaints-To: abuse@binc.net NNTP-Posting-Date: Wed, 3 Aug 2005 04:29:38 +0000 (UTC) Xref: g2news1.google.com comp.lang.ada:3919 Date: 2005-08-02T23:30:23-05:00 List-Id: In article , Jeffrey Carter writes: > 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. Or the formerly used parts of the disk that have been "revectored" in response to hardware problems. In summary, there is a large body of knowledge in this area that is not at all specific to Ada.