Message-Id:	<m0wIAP0-000Fm9C@hn.planet.gen.nz>
Date:	Fri, 18 Apr 97 21:56 NZST
Mime-Version:	1.0
To:	alaric AT abwillms DOT demon DOT co DOT uk
From:	Lorier <lorier AT ihug DOT co DOT nz>
Subject:	Re: Usage of directory entries
Cc:	Matthias DOT Paul AT post DOT rwth-aachen DOT de, opendos-developer AT delorie DOT com

>> 1k Clusters up to a Terabyte (I think, certainly more than a gig anyway),
>> where MS keep kluding FAT :(  With ext2 we can show a far more efficient
>> FileSystem and show how bloated FAT really is :)
>
>An extent based filer like VSTa uses or, I deduce, NTFS is (it uses
>512 byte allocation units) can be more efficient, I think; disk
>space is managed like malloc allocates blocks of RAM, in runs of 
>sectors. Unless it gets really fragmented, this is smaller than having 
>free-space bitmaps and indirection blocks and all that. And smaller
>means faster, no? :-)

Er, not always :) It's usually a trade off between Speed and Size, having to
do it that way means you have to do mass calculations, and also trying to
handle adding to to the end of a file is a problem if the next file is right
at the end, thus leading to high fragmentation :)

>(many UNIX filers are quicker at random access since having indirect
>index blocks helps the seeking into files business, but are slower
>for sequential access, since the index blocks have to be loaded.
>FAT is even slower than either of them!)

Anything has to be better than FAT :)

ext2fs is well used as a Linux filesystem which Caldera have a large
interest in :)  I'd just like a file system where your 1 gig drive doesn't
have a hundred meg or so of Slack Space, I could do just as well on a 800m
drive with no slack space :)  Although drive space isn't THAT expensive any
more... We haev to make a trade off somewhere, and ext2fs seems to do rather
well.

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