[Solved] Flaky DVD burning speed

[Qcumber-some]

Hi there,

I'm trying to make DVD burning work. I have 4 identical IDE burners on an nForce2 mainboard by ASUS and I'm trying to make these burn DVD-R stable at 4x speed. It doesn't even work with one, and gets worse (logically) if I try to burn on several ones at the same time.
I've checked some Howtos and lots of forum entries, and checked everything they mentioned (like the CONFIG_HZ_* options and IO scheduler), but it does not improve drastically.
- DMA is on.
- The correct nForce kernel option is compiled as static into the kernel. (SATA by the normal way (not the old SCSI interface), PATA by the old way, not the experimental one)
- Speed of the drives (by hdparm) is ok (6.5MB/s)
- IO scheduler change doesn't work (it is default at CFQ)
- I'm trying with wodim from an ISO from SATA file. Fifo buffer is always full (min. 97%) so it is not an issue of enough data to write.
- Testdrive with driver=dvd_simul works at 4x very stable.
- No buffer underrun warnings from wodim.
- Wodim says DMA speed is 24x DVD
- Wodim option --immed improves the result, but doesn't really make it work
- hda and hdb (primary controller) are quite stable, only fluctuating once every minute (then it goes down below 1.0x for a few seconds)
- hdc is worse, hdd is the worst, fluctuating 20 to 30x below 1.0x, making an average writing speed of 0.8x or 0.9x

The funny thing is - I had this system run an old SuSE9.3 before, but the HD died and so I installed Gentoo on it. The old SuSE9.3 could burn the same ISO (cached reads from VFS... great invention) to all four drives in 4x speed... The hardware did absolutely not change except the SATA harddisk (which got better - has been WD 100GB before, now Seagate 200GB).

Is there anything I'm missing? What else should I check?

I'm running a current Gentoo with a handmade gentoo-sources kernel 2.6.22-r9.

[didymos]

I'd suggest trying the new PATA drivers. They're not that experimental anymore, especially if you use a 2.6.23 kernel (at least one of which ought to marked stable by now). The Nvidia PATA driver isn't even marked as experimental anymore in menuconfig.
_________________
Thomas S. Howard

[Gusar]

Try increasing fifo size. 'wodim fs=32m' or maybe even 64m.

[Qcumber-some]

@didymos: I'm trying that right now... thanks for suggesting. I would not have tried it due to the experimental marking.

@Gusar: The fs=32m setting is already present. It doesn't change anything, the fifo buffer is always full (the minimum I've ever seen is 97%). Thanks for helping, though.

[Qcumber-some]

Solved it...
wodim just doesn't perform as well as cdrecord.

I emerged cdrecord and it worked just like in SuSE9.3 before.
Seems the wodim guys need to do a bit of homework

Thanks all for helping.