Packet Writing Very Low Throughput

[rickythesk8r]

Is there something really wrong here? I'm experimenting with older HP "high-speed" 12x cd-rw discs, but even tripling the speed to 36x with better media is not going to make much practical difference.

The throughput is an agonizing 2.5Kb/s. The files appear intact, though I don't have the patience to wait for more than about 1MB.

The drive is: hdc: _NEC DVD_RW ND-3550A, ATAPI CD/DVD-ROM drive

# cat /proc/sys/dev/cdrom/info
CD-ROM information, Id: cdrom.c 3.20 2003/12/17

drive name: hdc
drive speed: 40
drive # of slots: 1
Can close tray: 1
Can open tray: 1
Can lock tray: 1
Can change speed: 1
Can select disk: 0
Can read multisession: 1
Can read MCN: 1
Reports media changed: 1
Can play audio: 1
Can write CD-R: 1
Can write CD-RW: 1
Can read DVD: 1
Can write DVD-R: 1
Can write DVD-RAM: 0
Can read MRW: 1
Can write MRW: 1
Can write RAM: 1

Packet writing is compiled into the kernel. Udev creates the following devices when the system comes up:

$ ls -l /dev/pktcdvd
total 0
crw-rw---- 1 root cdrw 10, 63 Jul 28 16:23 control
brw-rw---- 1 root cdrw 254, 0 Jul 28 16:23 hdc
brw-rw---- 1 root cdrw 254, 0 Jul 28 16:23 pktcdvd0

sys-fs/udftools is
# equery l udftools
[I--] [ ~] sys-fs/udftools-1.0.0b-r7 (0)

$ cdrwtool -d /dev/hdc -g
using device /dev/hdc
ok, want to get
1312KB internal buffer
setting write speed to 12x
writing fixed packets
border type : 0
track mode : 7
data block type : 10
session format : 32
packet size : 32

Thanks in advance for any suggestions.

[eccerr0r]

I've noticed my drives vary quite a bit in terms of packet writing speeds on the same media. So far I've found my Pioneer DVR-106 most reliable at only 2x Rewriteable. My lite-on ldw-411s dvd-rw however, is extremely slow. The disk spins up and down and up and down constantly while writing the disk. This is the same disk that was in the Pioneer. I also have a Samsung 8x dvdrw-dl burner which didn't fare much better than the lite-on. (btw, this is all DVD-rewriteables not CDRW, and I suspect a similar issue is happening between them)

Because of the inconsistency of the packetwriting speeds I've basically stopped doing them and just masterring disks SAO. Even at 2X dvdrw speeds is kind of slow, plus I'm not sure how reliable it is.

Likely there's some packet size tuning that needs to occur but I don't recall any tuneables in pktcdvd. And it would need to be on a per-drive model basis...
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

[rickythesk8r]

I tried changing the packet size to 128 and it made matters worse, so I reverted to the defaults.

This is what cdrwtool outputs. First, "quick setup:"

# cdrwtool -d /dev/hdc -q
using device /dev/hdc
1312KB internal buffer
setting write speed to 12x
Settings for /dev/hdc:
Fixed packets, size 32
Mode-2 disc

I'm going to do a quick setup of /dev/hdc. The disc is going to be blanked and formatted with one big track. All data on the device will be lost!! Press CTRL-C to cancel now.
ENTER to continue.

Initiating quick disc blank
Disc capacity is 295264 blocks (590528KB/576MB)
Formatting track
start=0, blocks=16, type=RESERVED
start=16, blocks=3, type=VRS
start=19, blocks=237, type=USPACE
start=256, blocks=1, type=ANCHOR
start=257, blocks=31, type=USPACE
start=288, blocks=32, type=PVDS
start=320, blocks=32, type=LVID
start=352, blocks=32, type=STABLE
start=384, blocks=1024, type=SSPACE
start=1408, blocks=293568, type=PSPACE
start=294976, blocks=31, type=USPACE
start=295007, blocks=1, type=ANCHOR
start=295008, blocks=160, type=USPACE
start=295168, blocks=32, type=STABLE
start=295200, blocks=32, type=RVDS
start=295232, blocks=31, type=USPACE
start=295263, blocks=1, type=ANCHOR
Writing UDF structures to disc
Quick setup complete!

Next, "detailed disk info:"

# cdrwtool -d /dev/hdc -i
using device /dev/hdc
1312KB internal buffer
setting write speed to 12x

DISC INFO:
erasable : Yes
border = 3
Disc status = 2
number of first track = 1
number of sessions = 1
number of tracks = 1
status of last track = 1
uru = 0
did_v = 1
dbc_v = 0
disc type = 32
disc_id = 878373
lead_in = 255:255:255 (1166880)
lead_out = 255:255:255 (1166880)
OPC entries = 1

TRACK INFO:

Track 1
track_number = 1
session_number = 1
damage = 0
copy = 0
track_mode = 7
Rt = 1
blank = 0
packet = 1
fp = 1
data_mode = 2
lra_v = 0
nwa_v = 0
track_start = 0
next_writable = 4294967295
last_recorded = 0
free_blocks = 0
packet_size = 32
track_size = 295264 (590528KB)

[eccerr0r]

it's not just increasing the packet size or decreasing it, it needs to match that of how large the drive itself wants. I suspect it's doing read-modify-writes or something that causes it to be so slow. plus there may be some drive firmware that can't figure out how to resync the laser after writing a packet, potentially there is no solution except to just run it SAO...

How well does it work in Windows?
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

[rickythesk8r]