[tex-live] Re: Re: [tug-board] Any news of DVDs ?

[Reinhard Kotucha]

>>>>> "Karl" == Karl Berry <karl at freefriends.org> writes:

  >     Incidentally, 7-zip even has its own format (7z) which in many
  > cases packs much better than anything else.

  > Yeah.  If someone would like to try 7zipping the TL iso, I'd be
  > interested to know how it fares, both in how well it compresses
  > and in decompression time.

sizes
-----
The numbers in braces denote compression gain.  

    100 * (1-(compressed_size/iso_size))

714938368  TeXLive-2005-install.iso
684287622  TeXLive-2005-install.iso.bz2 (4.2872%)
682955930  TeXLive-2005-install.iso.zip	(4.4735%)
682955793  TeXLive-2005-install.iso.gz  (4.4735%)
677460837  TeXLive-2005-install.iso.7z  (5.2421%)

I suppose that in Hans' example the content of the ISO-images had not
been compressed.  Hence, compression gain depends much more on the
program than it does when the content of the image is already
compressed.


compression
-----------
~ $ time 7z a TeXLive-2005-install.iso.7z TeXLive-2005-install.iso
real    9m0.143s
user    8m32.876s
sys     0m7.664s

~ $ time bzip2 TeXLive-2005-install.iso 
real    5m39.139s
user    5m4.735s
sys     0m4.760s

~ $ time gzip TeXLive-2005-install.iso
real    1m1.198s
user    0m43.491s
sys     0m3.400s

~ $ time zip TeXLive-2005-install.iso.zip TeXLive-2005-install.iso
real    0m58.736s
user    0m41.075s
sys     0m3.596s


de-compression
--------------
~ $ time bunzip2 TeXLive-2005-install.iso.bz2 
real    2m25.975s
user    2m2.304s
sys     0m4.644s

~ $ time 7z -y e TeXLive-2005-install.iso.7z
real    1m33.379s
user    1m7.852s
sys     0m4.216s

~ $ time unzip -o TeXLive-2005-install.iso.zip 
real    0m30.398s
user    0m6.184s
sys     0m3.260s

~ $ time gunzip TeXLive-2005-install.iso.gz 
real    0m30.952s
user    0m6.492s
sys     0m3.724s



I must admit that I did not read all the documentation.  I don't use
zip very often and installed 7-zip just after I read your mail.  The
7z manual page is quite short and refers to additional documentation.
At least there is a command line option which allows you to select a
compression algorithm.  Maybe some of the programs can be tweaked to
fit a particular need.

(Look at the previous paragraph.  Seems that Emacs does character
protrusion now :) 

It seems that in this particular case (compressing an ISO-image which
contains compressed files), it does not really matter very much which
compression scheme is used, there is only a more or less significant
difference between compressed and uncompressed files.

It also seems that for TeXLive-2005-install.iso it doesn't make much
sense to provide anything else but zip.  It compresses even better
than bzip2 and de-compression speed is much better.

As far as CTAN is concerned, Robin provides all the packages as zip
files.  He asked before he made this decision and nobody complained.
It is desirable that everything on CTAN is available as zip.

There is certainly no problem to provide the images in different
formats at http://tug.org as we do at http://vntex.org . But there,
the differences between zip and bz2 are more significant.  For the
TeXLive-ISO it only makes sense to consider whether providing a
compressed version or not, thinking too much about which algorithm
to use certainly means wasting time.

Regards,
  Reinhard

-- 
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Reinhard Kotucha			              Phone: +49-511-4592165
Marschnerstr. 25
D-30167 Hannover	                      mailto:reinhard.kotucha at web.de
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