[tex-live] Speed of DVD-reads

[Oliver Bandel]

Hello,

tonight I did some speed-tests on DVD-reading-times
of DVDs/CDs on my Linux-PC.

I didn't used special speed checkers, I just used hdparm.
In the hdparm manpage is mentioned one has to use it
more than once to get valid results.

So I did then.


Here are some results I got:


Solaris-DVD                                8,8 MB/s
(Solaris Express, Developer Edition)

BSI-CD (Sichere Informationstechnik        2,9 MB/s
für unsere Gesellschaft)

TeX-Live-DVD 2007 (DVD)                    2,6 MB/s

Solaris-DVD (like above, but "Preview")    4,9 MB/s


The DMA and 32-Bit settings had no influence on
the TeX-Live-reading-speed. But it had influence
on reading speeds of the Solaris-DVDs.
(The faster could be read slower and the slower faster.)

All values above were done with the default values,
which were set automatically after booting.

As you can see, there are speed-factors of aup to
about 3.4 between different DVDs.

So it looks like the TeXLive-DVD is not such a good one.
When low reading speed comes together with a disk-image
that is not so good and an installation script that
often does re-read informations from the disk and also
uses a lot of fork/exec-stuff (shells/subshells/calling external
programs instead of e.g. Perl-builtin-functions for String-matching)
then this all together wastes performance and time.

The installation-time could be much better, when the DVD could be
read as fast as the Solaris-DVD for example.

As hdparm seems to read a bigger chunk of data at a time,
this can't be compared directly to reading-operations,
where individual directories and files must be read.
So, installing a lot of single files seems to be much
slower than what hdparm offers here.

Ciao,
   Oliver