[tex-live] Question about TeX Live Installation

Manfred Lotz manfred at dante.de
Sun Feb 12 08:47:30 CET 2006

Hi Karl,

On Wed, 8 Feb 2006 21:11:36 -0600
karl at freefriends.org (Karl Berry) wrote:

>     just a thought ... it's a dual layer dvd, isn't it? So what if the
>     data is on one layer and the index on another?
> I have no clue about the physical possibilities of the DVD.  Manfred?

Yes, it could happen that  some data file is on the one layer and
the accompanying index file is on the other.

FIrst, if the double layer DVD could make installation of e.g. TeXLive
painfully slow due to data residing on different layers then the
installation from the plain TeXLive DVD (ehich isn't double
layer) shouldn' be a problem. Right?

When burning a double layer dvd first an iso image will be created by
using mkisofs. At this tage we have no notion of layers. That comes
later when a premastering will be done. 

Premastering is hidden when the burning is done by a drive which is
capable of burning  a DL DVD. I did like this for the TeX Collection

In this process I do not see any possibility of directing files to a
specific layer. 

I would assume that for burning the iso image on a DL DVD the iso image
just gets cut in two pieces for the two layers. This means that likely
two files residing in the same directory will happen to live on the
same layer on the DVD. Exception might be a directory which starts at
the first layer and ends at the second layer.

The question now is if mkisofs could be told to keep certain files
"together" (keeep in mind there is no notion of layers for mkisofs)

What I've found is (from the man page of mkisofs):

  -sort sort file
              Sort file locations on the media. Sorting  is
controlled  by  a file that contains pairs of filenames and sorting
offset weight- ing.  If the weighting is  higher,  the  file  will  be
located closer to the beginning of the media, if the weighting is lower,
              the file will be located closer to the end of the
media.  There must  be  only  one space or tabs character between the
filename and the weight and the weight must be the last characters  on
a line. The filename is taken to include all the characters up to,
              but not including the last space or tab  character  on
a  line. This is to allow for space characters to be in, or at the end
of a filename.  This option does not sort the  order  of  the  file
              names  that  appear in the ISO9660 directory. It sorts
the order in which the file data is written to the CD image - which may
be useful  in  order  to  optimize  the  data  layout  on a CD. See
              README.sort for more details.

Perhaps this gives us a possibility to keep certain files together on
one layer by giving them equal weights.

The iso image of the TeX Collection 2005 had the following order of
directories from a mkisof's point of view:
/ctan    		( 4368186 ) 
/texlive  		( 1245653 )
/protext  	( 691000 )
/mactex  	( 659665 )

In parenthesis I've included ths sizes of the directories.

>From this I would assume that the directory of the iso file system and
the ctan stuff are on the same layer. This would imply that for
installing TeXLive, ProTeXt or MacTeX it has to be switched constantly
between the layers which is especially bad in the case of many small

If my thoughts are no too far from reality I should be able to do the
Creating a DL DVD putting /texlive, /protext and /mactext
on the first layer and testing an installation of TeXLive to see if
this makes it faster.


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