long and boring explanation of lzma modules and compression (ignore it - I post it beacause I think I should)

[Zbigniew Luszpinski]

Hello,

lzma is going to be future packer - compression better than bzip2 and 
decompression speed similar to gzip. lzma is packer of choice for many new 
distros custom packages format and rpm5.

I have just uploaded lzma and lzma-sdk module to moonbase.
lzma is fully syntax compatibile with gzip/bzip2 syntax standard. This means 
you can use lzma command using the same parameters like for gzip or bzip2.
lzma-sdk is directly compiled with cutting edge new 7zip SDK when compared to 
a little bit older lzma module tools. To avoid conflict lzma from lzma-sdk 
module, the command is called lzma-nongnu to clearly show the difference in 
syntax which is similar to 7z packer.

The attached unpack-generic.plugin.patch only adds *.lzma datatype to generic 
unpacker lunar plugin. lzma module dependency required for lunar module to 
make it working.

lunar-lzma.patch.lzma attachment is serious rewrite of whole lunar module to 
support lzma everywhere instead of bzip2. This should be soft transition as 
present bziped logs and archived modules are still availabe for using but new 
stuff is exclusively written as *.lzma files. I have made some tests to check 
if lzma is really so good by compressing moonbase. The default levels of 
compression of lzma looks no really better than default bzip2:
975K moonbase.tar.bz2 default bzip2 compression
984K moonbase.tar.lzma.std default lzma compression
955K moonbase.tar.lzma9 best -9 lzma compression
root at localhost # time bunzip2 moonbase.tar.bz2
real    0m1.157s
user    0m1.072s
sys     0m0.044s

root at localhost /budowa/packer # time lzma  moonbase.tar.lzma.std
real    0m1.682s
user    0m1.608s
sys     0m0.024s

root at localhost /budowa/packer # time lzma  moonbase.tar.lzma9
real    0m1.779s
user    0m1.684s
sys     0m0.056s

Because I'm not satisfied with default compression of lzma and decompression 
time when compared to bzip2 I stopped working on Lunar module and left it "as 
is". That is why it is compressed with lzma to protect against accidental 
use without having lzma installed. If someone is interested in testing or 
continuing the work - he/she is welcome. I'll keep an eye on lzma development 
to see if some day it will have better default compression of moonbase.

zbiggy
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