I tried to use newfs_udf from the misc/udfclient package on a DVD+RW
disc (newfs_udf -L test /dev/rcd1c), and after working for a while
(don't know how long, but less than a minute), it gave a stream of
HELP! got writing error while writing; can't fix yet! (Input/output error)
errors. I checked the kernel message log, and found:

Sep 29 03:23:57 yerfable /netbsd: cmdide0:0:0: lost interrupt
Sep 29 03:23:57 yerfable /netbsd: 	type: atapi tc_bcount: 65536 tc_skip: 0
Sep 29 03:23:57 yerfable /netbsd: cmdide0:0:0: bus-master DMA error: missing interrupt, status=0x21
Sep 29 03:23:57 yerfable /netbsd: cmdide0:0:0: device timeout, c_bcount=65536, c_skip=0
Sep 29 03:23:57 yerfable /netbsd: cd1: transfer error, downgrading to PIO mode 4
Sep 29 03:23:57 yerfable /netbsd: cd1(cmdide0:0:0): using PIO mode 4

Device timeout? Does some timeout in the kernel need to be increased?
I'm not sure what c_bcount is, but if it's the number of sectors it's
trying to write, with a 2K sector size, that's 128MB, which I think
would take about 47 seconds to write to 2X DVD+RW media
(dvd+rw-mediainfo says: Write Speed #0: 2.0x1385=2770KB/s)

FWIW, I haven't had any problems writing with growisofs or dvdrecord.

My system:

NetBSD 2.0_BETA (YERFABLE) #211: Thu Sep 16 15:18:43 CDT 2004
        khym@yerfable.azeotrope.org:/usr2/obj.alpha/sys/arch/alpha/compile/YERFABLE
[ ... ]
cmdide0 at pci0 dev 11 function 0
cmdide0: CMD Technology PCI0646 (rev. 0x01)
cmdide0: bus-master DMA support present
cmdide0: primary channel wired to compatibility mode
cmdide0: primary channel interrupting at isa irq 14
atabus2 at cmdide0 channel 0
cmdide0: secondary channel wired to compatibility mode
cmdide0: secondary channel interrupting at isa irq 15
atabus3 at cmdide0 channel 1
[ ... ]
atapibus0 at atabus2: 2 targets
cd1 at atapibus0 drive 0: <DVD-RW IDE1008, , VER 005> cdrom removable
cd1: 32-bit data port
cd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 4 (Ultra/66)
cd1(cmdide0:0:0): using PIO mode 4, DMA mode 2 (using DMA data transfers)

-- 
Name: Dave Huang         |  Mammal, mammal / their names are called /
INet: khym@azeotrope.org |  they raise a paw / the bat, the cat /
FurryMUCK: Dahan         |  dolphin and dog / koala bear and hog -- TMBG
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