From owner-freebsd-hackers Mon Feb 5 06:45:21 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id GAA00662 for hackers-outgoing; Mon, 5 Feb 1996 06:45:21 -0800 (PST) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id GAA00656 for ; Mon, 5 Feb 1996 06:45:04 -0800 (PST) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id PAA21079; Mon, 5 Feb 1996 15:34:24 +0100 From: Luigi Rizzo Message-Id: <199602051434.PAA21079@labinfo.iet.unipi.it> Subject: Re: Some thoughts on FAT filesystems To: rnordier@iafrica.com (Robert Nordier) Date: Mon, 5 Feb 1996 15:34:24 +0100 (MET) Cc: hackers@freebsd.org In-Reply-To: <199602051254.OAA00269@eac.iafrica.com> from "Robert Nordier" at Feb 5, 96 02:54:05 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@freebsd.org Precedence: bulk > On Mon, 5 Feb 1996, Luigi Rizzo wrote: > > > Since some people is now looking at the msdosfs, it is nice that > > the discussion on FAT has progressed a little bit. > > > > I'd like to contribute some more thoughts. In the following I assume > > that there are no concurrent accesses to the FAT partition. > > New ideas, or combinations of ideas, are always interesting. :-) > > As the new kid on the block, I think the filesystem you describe would > have to show how it is superior to two existing, FAT-incompatible contenders > for the title of Improved FAT FS: the HPFS (OS/2) and NTFS (Windows NT). > > The HPFS makes use of a banding system similar to the one you describe. > Both HPFS and NTFS also make use B-Trees in place of unsorted directories. this is a nice idea, I didn't go this far... > NTFS features transaction logging to support better filesystem recovery, > and both support hot-fixing (transparent recovery from media errors). > Etc.... > > Of course, what we really need is a vastly improved FAT filesystem that > makes use of FAT-identical data structures, and also is algorithmically > similar to all MS-DOS versions in every respect. :-) All the suggested changes can be done by keeping the FAT as the raw data, and adding structure info within files. If they exist, you just go faster. If they don't, you go slower and probably ought to get some nice reminder at mount time that suggests you to run "mkImprovedFATFS" next time... Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================