DVD-RAM, UDF => very slow

[Gert Brinkmann <gelberschnee@gmail.com>]

Hello,

I am using an up to date debian/sid with kernel 2.6.14-2-k7 (if it is
running) or (currently) 2.6.12-k7. When writing to an DVD-RAM using a
internal IDE NEC-4550 Device data is written with only 600-880 KByte/s
where it should be 2 MByte/s (with an 3x DVD-Ram from Panasonic).

I have tried several block sizes and got the following rates:

mkudffs -b 1024 -r 0x0201 --media-type=dvdram /dev/hdc
=> 883 KByte/s

mkudffs -r 0x0201 --media-type=dvdram /dev/hdc
=> 724 KByte/s
(Blocksize is 2048 per default)

mkudffs -b 4096 -r 0x0201 --media-type=dvdram /dev/hdc
=> 614 KByte/s


Using tar to directly write to the device was faster when using a
blocksize of 4096 (=> 1766 KByte/s). Astonishing with a blocksize of
2048 (what I thought would be optimal) it is slower (1046 KByte/s) but
still faster than UDF.

Does anybody know where might be the problem? I have read that a
performance problem came with kernel 2.6.7. Is this true? Are there any
patches to speed up DVD-Ram writing with current kernels?

Thanks,

Gert