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Re: Size matters. 7zip. Again.

"rzip is not for everyone! The two biggest disadvantages are that you can't
pipeline rzip (so it can't read from standard input or write to standard
output), and that it uses lots of memory. A typical compression run on a large
file might use a couple of hundred MB of ram. If you have ram to burn and want
the best possible compression rate then rzip is probably for you, otherwise
stick with bzip2 or gzip."

I'm not sure whether not being able to pipeline it might be a problem, but
needing that huge amount of RAM might, at least in my oppinion. I'm not sure
if they're refering just to compression or both to compression and
decompression anyway.

Decompression doesn't take more memory than bunzip2 (in fact: less). I've tested the openoffice orig.tar from sarge and just watched top to get an idea. The only big issue is the needed memory for compression. My 256 MB machine needed very much swapping to finish the execution.

The compression rate is not neccessarily better for rzip compared to bzip2: (The uncompressed tar file as about 1.2 MB)

170374 logwatch_7.2.1.orig.tar.bz2
218476 logwatch_7.2.1.orig.tar.gz
173941 logwatch_7.2.1.orig.tar.rz

If you want to test this file, it's available from http://pkg-logwatch.alioth.debian.org/apt/pool/main/l/logwatch/

another example where rzip performes better:

141769841 openoffice.org_1.1.3.orig.tar.bz2
122258088 openoffice.org_1.1.3.orig.tar.rz
165M for the tar.gz
the uncompressed archive has about 610 MB

My conclusion is that rzip is not suitable for debian (source) packages, binary would one testing) because the compression for bigger is not feasable on machines with low ram (and even 256MB seem to be low RAM for rzip) and the compression rate is not so impressing.


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