Hello,
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:
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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
file.
* 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.
<my_comment>
This is, was I had in mind.
</my_comment>
* 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.
<my_comment>
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?
</my_comment>
* or directly read it in to internal structures
<my_comment>
Oh, he says it ;-)
</my_comment>
* 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.
<my_comment>
Is there no kernel cache for CD/DVD?
For harddisk there is (should be) one...
</my_comment>
* 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.
<my_comment>
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.)
</my_comment>
* 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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Ciao,
Oliver