Well here's my findings of facts :

the machine : a compaq proliant 800 2x PIII 500MHz/512kb (Katmai)
              128 Mb RAM, 2x 9.1Gb U2W SCSI
              _NEC DVD_RW ND-2510A Dual Layer burner

i installed a vanilla suse9.1, and tried to read a 4.5Gb dvd isoimage
to disk using the command :

# readcd -v dev=ATAPI:0,0,0 f=dvdimage.iso

and afterwards try to  burn it to a dvd-r recordable using this command:

# cdrecord -v dev=ATAPI:0,0,0 driveropts=burnfree -dao dvdimage.iso

Not only did the suse9.1 kernel 2.4.5 _NOT_ switch on DMA on that burner
,it was terrible SLOW, i got only 2Mbytes/sec. On a different machine a
dual xeon machine with 1024Mb RAM, suse91 even failed to read the dvd
iso image, always failing at the moment 1024Mb physical was getting 100%
into use. The readcd process then locks hard , and one cannot kill it.
When the readcd command was running, one was not able to operate the
SuSE91 machine interactively in a normal fashion. Apparently the reiserfs
root filesystem doesn't like a single huge file of 4.5Gb being written
onto.

This behaviour reminds me closely of SCO OpenServer 5.0.x where making a
backup on tape, renders the application software not usable.

Apparently the virtual memory management behaviour of SuSE9.1 was
seriously lacking. Actually so bad, that my only conclusion is that
the SuSE 9.1 kernel is seriously broken.

To put this to the test i installed on the same proliant 800, Mandrake
10.0. And not only does the Mandrake kernel switch on DMA on the NEC 2510A
Dual Layer burner, it reads the 4.5 Gb dvd iso image at a speed of 7.7
Mbytes/sec. That is on the same machine but only installing mandrake 10.0
instead of suse91. I used these RPMS for Mandrake 10.0 :

http://crashrecovery.org/oss-dvd/RPMS/mdk100/

Burning went at normal speed hovering between 6x to 8x .

I am so bitterly disappointed at SuSE9.1 , that for some time I was
thinking if Novell uses this SuSE disaster edition (9.1) as a way to
discredit Linux. This of course can not be the case.. Anyway, as of now i
dropped all SuSE related stuff and papertrail attached, as i simply cannot
take such a drama seriously.

regards,

Robert
--
Robert M. Stockmann - RHCE
Network Engineer - UNIX/Linux Specialist
crashrecovery.org  st...@stokkie.net