[tex-live] The suggestions (from tex-d-l) (Re: Comment on Re: TeXLive-CD/DVD (Installation))

Oliver Bandel oliver at first.in-berlin.de
Wed May 23 13:15:53 CEST 2007


On Wed, May 23, 2007 at 12:03:20PM +0200, Oliver Bandel wrote:
> I now will reread the tex-dl-Thread and look for the ideas, the people
> provided there to make the installation better (e.g. better dvd-image).
> I will gather the stuff and translate to english then and send it to this
> list here.

The two most interesting/informative mails from the discussion on the
tex-d-l list came from Markus Kohm.

I have translated his ideas and inserted some comments.

See below:


First Mail:
Markus Kohm mentioned, that for the last TeX-livedistribution
there were similar discussions.

He said, there are some problems:

 * there are very much single packages, each consisting of one compressed
 * The files are not on the DVD in the order, in which they will be read.

 * that means a lot of seek-actions on the DVD

 * each package must be uncompressed individually

 * the last time the texlive was made (last distribution), somone
   tested, if it's faster to create an image from the DVD on the
   harddisk and install from the directly mounted image.
   It was much faster.

 * Instead of an image of the DVD to mount directly, it should also
   work, first to copy the DVD's files to disk and install from disk.
   The disadvantage is, that reading the files from DVD (cp to harddisk)
   also has the same problem as before: maybe the files are not in the
   necessary order to read on the DVD.

 * maybe the installtaion could be speed-up by the following:
   - the packages that will be installed will be put into the DVD-image
   in that order, in which they will be read during installation.

 * When the isntallation runs, they will be copied in this order to harddisk,
   and then installed from there.


Second Mail:

In another Mail Markus Kohm wrote this:

  * first one has to look for dependencies of Schemes, Collections and Packages

  * then: the non-dependent packages in Schemes and Packages must always be in
    the same order on the DVD.
  This is, was I had in mind.

  * They also have to be installed in the same order

  * also it should be avoided to read one file more than once.
    For example all needed tpm-files should be (temporarily) copied to harddisk
    the first time they will be touched.
    And the next time when they will be read they should be read from
    harddisk, not from DVD.

     Why will they be read more than once?
     Does the installation-script not buffer the data?
     No memeory usage? Instead again and again using
     shell/sd/grep for every individual Regexp-Lookup?
     (This btw. was what I thought, when I looked into install-tl.sh,
      that it does all things unnecessary often.)

     My idea would be: do we need these tpm-files on disk? Why not
     reading it to memory, if they are used so often?

  * or directly read it in to internal structures

  Oh, he says it ;-)

  * problematic is here, that regarding the file-access-operations
    one depends on the OS's actions. If the OS must reread managing-infos
    for each file again and again to find out, where the files are on
    the DVD, then all is lost from the beginning on.

  Is there no kernel cache for CD/DVD?
  For harddisk there is (should be) one...

  * a simple solution would be, to have the packages in alphabetic order
    and write them in that order to the DVD-image; installation from there
    then in this order to disk, and installing from disk.

  Sorting alphabetically is a simple idea, but I think this could be a good way.
  (It could be any other order, as long as reading from the DVD is the same
   as the data are ordered on the DVD. Using an alphabetical orer is nice,
   because one also can see at the names of the installed files, how far the
   progress of instalation is. So IMHO this is very good.)

  * Disadvantage: a lot of additional space on the harddisk is needed.

  * Advantage: less access to directories and other managing-information.

  * well, the complete process should be done automatically, so it might
    make sense to write a software for this.



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