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Re: [debian-knoppix] Compressed filesystem

On Wed, Oct 09, 2002 at 11:46:13PM -0700, Rib Rdb wrote:
> I'm sorry, my German isn't very good so I have to
> write this in English.  I am building a system similar
> to Knoppix.  Is there any reason you used isofs for
> the compressed image?

Yes, because it is
- read optimized
- stable
- loopback mountable
- supports all necessary Unix features like devices,
  sockets and symlinks
- has no maximum filesystem size limitations.

> With my 300 mb uncompressed
> iso, I save about 1.5% by converting it to romfs and
> then compressing compared to a compressed iso.

How did you do the compression in both cases? Both with

> This
> extra space could help on larger images.  Also, is
> there any advantage to using cloop over using zisofs? 

Yes. zisofs is a compressed filesystem, cloop is a compressed
block device. Compressed filesystems are slower, because each file has
to be uncompressed again in each read, while cloop keeps the
uncompressed blocks in the normal block layer filesystem cache.
cloop is older, well-tested and filesystem independend.

You may want to run some benchmarks to compare speed, if you like,
please mail the results to the list. :-)

-Klaus Knopper
debian-knoppix mailing list

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