*BSD News Article 74355


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Getting the most capacity out of Floppy Disks.
Date: 21 Jul 1996 08:53:38 GMT
Organization: Private BSD site, Dresden
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eyager@novagate.com wrote:

> When I formated at 1.44M floppy disk and created a new files system on
> it, I only got a capacity of around 860K.  That means that almost half
> of the disk is wasted to store file system information!  How can I
> tweak the filesystem parameters so that I can increase the capacity to
> a more rational level without having to sacrifice long file names or
> random access to files?

Why do you wanna sacrifice that?

Either, you can pick something like tar(1), and write directly to the
floppy.  This avoids the filesystem, and gives a fairly generic data
exchange medium for almost all Unices.

If you need a filesystem floppy, you're suffering from an idiosyncrasy
of Unix filesystems that they cannot dynamically convert between inode
(administrative) and data space.  Thus, you have to allocate inode
space at time of filesystem creation.  In your case, you've simply
been wasting way too much space there.  Have a look at the output of
df -i to see the inode space.

Here's the comment from /etc/disktab about floppies:

# To make a filesystem on a floppy:
#	fdformat [-f <size>] fd<drive>[.<size>]
#	disklabel -B -r -w fd<drive>[.<size>] fd<size>
#	newfs <opts> fd<drive>[.<size>]
#
# with <opts>:
#	-t 2	- two heads
#	-u 9|15|18 - sectors per track
#	(using the default value of 1/4096 is not much useful for floppies)
#	-l 1	- interleave 1 (for most floppies)
#	-i 65536 - bytes of data per i-node
#	(the default -i value will render you with a floppy wasting way
#	too much space in i-node areas)
#

Instead of -t 2 -u 18, you can also use -t 0 -u 0 to force newfs
picking the values from the disklabel.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)