[CALUG] CDwriters

[Bart Nielsen]

I've got a 5 year old computer, and I've always envied the faster speeds
with the newer CD writers.  (Mine would write at about 4x --- a little
slower than the newer ones on the market today.  But I used to say "but
it works well..." and let it go at that.)

Well --- it worked well till Monday.

I tried buying a DVD writer a few months ago (maybe 6), and found that:

* Yes, the firewire port works...(neat --- it was the first time I've
had a firewire device to play with), as does the USB ports (I knew
that), but the internal DVD writer didn't work as either an internal or
an external device.  (It was suggested by my friends that perhaps
getting the IDE traffic off the internal bus would speed up the
processor and I'd get better performance.  I didn't realize you could
turn a DVD+RW into a coaster --- I'm guessing it was the copy protection
issues and there is section of the drive that they expect to be written
exactly once.  So, when I wrote it poorly because my computer is slow,
well, it was game over for that device...)

But it led me to believe that I didn't want to try that experiment again
till I have a faster computer, which isn't happening right now.  Maybe
in a few months...


So I went to BEST BUY and bought a new writer.  They had two that looked
like they would work --- and the Memorex writer was initially priced $
10 less than the Sony, and had 4x the buffer space, so it looked like a
winner.

I've been using cdrecord to write the disks (all of the gui's tend to
use that so fill in the name of your favorite gui here if it makes you
feel any better), and readcd -c2scan to check the accuracy.  I had a
much better disk with the new writer --- but it still wasn't perfect. 
(It reported 0.000400 % errors --- which I figured would be less than
0.5 seconds for the 10 hours of MP3's that I had stored on the cd.)

Except when I actually listened to my CD, the errors were arranged such
that I dropped some of the 10 minute tracks entirely --- so I lost a lot
more than the raw numbers suggested I should.


I just went back to BestBuy, and told them that I wanted to try
something else.  They were really easy to work with --- even though I
had already mailed in the rebate, they took back my box (I had trouble
with that at CompUSA 5 years ago --- they sold me a Pacific Data
CDwriter that was usb based for my wife's mac, and when I finally
openned it, there was a note that said "yup --- we know we said it would
work, but it won't".  For a month, they still thought it would, but
after that, they wouldn't even admit that it might work some time.   But
they wouldn't take it back because I had asked for a rebate, thus, I
didn't have the scan code --- and, well, anyone want a rarely used
USB-based (usb1) CD writer?  It's been resting at my home since then.


So, the other writer is a Sony writer --- same specs, but it has 25% of
the buffer space.  I don't have a lot of experience with the new drive,
but the result of readcd -c2scan was 'better' than I've seen for any of
my other drives as of late, namely:


CDB:  BE 00 00 04 91 D3 00 00 2E FA 00 00
status: 0x2 (CHECK CONDITION)
Sense Bytes: 70 00 05 00 00 00 00 0A 00 00 00 00 64 00 00 00
Sense Key: 0x5 Illegal Request, Segment 0
Sense Code: 0x64 Qual 0x00 (illegal mode for this track) Fru 0x0
Sense flags: Blk 0 (not valid) 
cmd finished after 0.063s timeout 40s
readcd: Input/output error. Cannot read source disk
readcd: Retrying from sector 299475.
.............................................
readcd: Input/output error. Error on sector 299519 not corrected. Total
of 1 errors.
readcd: -noerror set, continuing ...
.
readcd: Input/output error. Error on sector 299520 not corrected. Total
of 2 errors.
readcd: -noerror set, continuing ...
addr:   299521
Time total: 210.412sec
Read 773957.58 kB at 3678.3 kB/sec.
Total of 2 hard read errors.
C2 errors total: 0 bytes in 0 sectors on disk
C2 errors rate: 0.000000% 
C2 errors on worst sector: 0, sectors with 100+ C2 errors: 0

real	3m30.832s
user	0m0.668s
sys	0m3.591s


I tried mounting both my iso image in loop back mode and the new drive,
and then running diff against both file systems:

time diff -r . /media/dvd

real	5m13.197s
user	0m3.208s
sys	0m30.989s


So, it looks better than what I saw before.

I read the image in with dd:

time dd if=/dev/dvd of=xxx.iso
dd: reading `/dev/dvd': Input/output error
1198080+0 records in
1198080+0 records out

real	4m53.773s
user	0m2.151s
sys	1m7.999s


and while the input file (iso-10.iso) and the output file (xxx.iso) are
slightly different:

613414912 versus
613416960 bytes

cmp -b xxx.iso iso-10.iso
cmp: EOF on iso-10.iso
linux:> 


It looks like those differences aren't significant.




I wondered if anyone else had experience with this sort of thing.  If
the CDwriter mostly works, I'm going to drop it --- but I'm surprised
that a drive with a smaller buffer is doing a better job than a drive
with a larger buffer.  (Maybe skill in using the buffer makes more
difference than the buffer size itself?)

Comments?  (It looks like, for my system, today, I'm happier with the
Sony drive --- but which drive would you buy, and why?  I opted against
a DVD writer combo because I anticipate that when I want to do that,
I'll buy a complete system that has a DVD/CDwriter integrated, and the
extra $ 10 - 50 wouldn't ever be recouped by me because I'll never be
able to use the added functionality (unless I really want to turn more
DVD's into coasters...)

Bart.