Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!uunet!snorkelwacker.mit.edu!linus!linus!mwunix.mitre.org!jcmorris From: jcmorris@mwunix.mitre.org (Joe Morris) Newsgroups: comp.os.msdos.apps Subject: Re: Disk Manager and MSDOS 5.0 Message-ID: Date: 21 Jun 91 19:04:45 GMT References: <1991Jun17.100115.31473@kuhub.cc.ukans.edu> <1991Jun17.221311.15797@aplcen.apl.jhu.edu> <1991Jun18.091756.31516@kuhub.cc.ukans.edu> <4862@cocoa46.UUCP> Sender: news@linus.mitre.org (News Service) Organization: The MITRE Corporation, Bedford MA Lines: 23 Nntp-Posting-Host: mwunix.mitre.org For those of you who've been following the thread about low-level formatting of hard disks check out the issue of PC Magazine which just came out. (My copy is at home, so I can't tell you the date.) One of the articles explains why some disks (various models, various vendors) cannot be successfully low-level formatted in the field. As I recall this thread was started by a user who took an IBM disk, low-level reformatted it for use on another system, and now cannot reformat the disk to work with the IBM controller. The article seems almost tailor-made to respond to that query. In short, some disk/controllers use servo information recorded on the disk to control the head radius and to compensate for both short-term (thermal) and long-term (wear) drift. Without special hardware which is unlikely to be anywhere but a manufacturer's facility or a large repair shop, these servo tracks cannot be written in the field by controllers which expect to use them. Other controllers, however, know nothing about servo tracks and cheerfully overwrite them if instructed to do a low-level format. The result is that the disk, once the servo tracks are destroyed, cannot be used with a controller which expects those tracks to exist, and the controller is incapable of writing those tracks even in a low-level format. Joe Morris