Date: Thu, 29 Aug 1996 18:02:38 +0200 (MET DST)
From: Mark Habersack <grendel AT ananke DOT amu DOT edu DOT pl>
Reply-To: grendel AT ananke DOT amu DOT edu DOT pl
To: Orlando Andico <orly AT gibson DOT eee DOT upd DOT edu DOT ph>
cc: Alexander Lehmann <lehmann AT mathematik DOT th-darmstadt DOT de>, djgpp AT delorie DOT com
Subject: Re: Next DJGPP release (was: Emacs for DOS)
In-Reply-To: <Pine.SGI.3.93.960829153810.1208A-100000@gibson.eee.upd.edu.ph>
Message-ID: <Pine.NEB.3.95.960829175547.15952D-100000@ananke.amu.edu.pl>
MIME-Version: 1.0
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On Thu, 29 Aug 1996, Orlando Andico wrote:

>Perhaps some enlightenment can be drawn from the VFAT driver in Linux 2.0
Accessing the LFNs is not a problem. The problem lies in the need to gain
direct access to HD on the sector level in several OSs. Another problem is the
"checksum" field in LFN entry which I don't know how to generate (all I know
is that it is generated based on the 8.3 DOS name - but how?)

>kernel. Of course that is an inode-based implementation. I was wondering
>in fact if Linux could use VFAT as its native filesystem, ala UMSDOS but
>better since VFAT has LFN support etc.
Well, FAT (and even VFAT) is one of the slowest systems available. It
requires, at many spots, to browse the entire cluster chain of the file to
access appropriate sector and byte of the file data. Besides FAT doesn't have
any file protection, and is not as flexible as ext2fs (or for that matter any
i-node based FS). Another thing is that the slack in FAT-formatted drives is
very large - you loose up to 30% of your disk space (of course it depend on
what size files you store). If you wanted to reduce the slack and allocate
1024B clusters (like in ex2fs, for example) you'd end up with enoromous FAT
(x2). Last but not least, you can't implement one great feature of many i-node
based FSs: fragments. FAT is just not suitable for that kind of allocation
scheme.

Mark

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