After I posted some time ago in these groups about the potential to
create an EFS image on DVD media, I did some experiments in this
direction recently:

Pioneer DVD-303S (1.10 and 2.00 firmware revision) fails because data
cannot be read correctly from DVD media in 512 Bytes/sector mode.

Toshiba SD-1401 (1007 and 1010 firmware revision) fail because data
cannot be read at all from DVD media when requesting 512Bytes/sector.



Fortunately these problems can easily be investigated by reading from
the vol device file with dd.

hinv excerpt:
Integral SCSI controller 0: Version WD33C93B, revision D
Disk drive: unit 1 on SCSI controller 0
CDROM: unit 3 on SCSI controller 0
Tape drive: unit 4 on SCSI controller 0: DAT
CDROM: unit 6 on SCSI controller 0


Pioneer DVD-303S (2.00 firmware, but I think 1.10 was exactly the
same, I tried that some time ago):

# dd if=/dev/rdsk/dks0d6vol of=/var/tmp/dvd_image.303s.512 bs=512 \
count=160
160+0 records in
160+0 records out
# dd if=/dev/rdsk/dks0d6vol of=/var/tmp/dvd_image.303s.2048 \
bs=2048 count=40
40+0 records in
40+0 records out
# cmp dvd_image.303s.2048 dvd_image.303s.512
dvd_image.303s.2048 dvd_image.303s.512 differ: char 33281, line 2

the difference does appear to result from an off-by-one error in the
Pioneer Firmware: where dd bs=2048 will read a (virtual) sequence of
512 Byte sectors I call 1234567..., dd bs=512 will rather read
1123456... . That the error manifests itself at byte 33281 is because
the DVD I used in this example has an all zero bytes first sector of
32k size.

This does of course also hint at a possible "dirty" hack to prepare

Toshiba SD-1401 (1007 and 1010 firmware):

# dd if=/dev/rdsk/dks0d3vol of=/var/tmp/dvd_image.1401.2048 bs=2048 \
count=40
40+0 records in
40+0 records out
# dd if=/dev/rdsk/dks0d3vol of=/var/tmp/dvd_image.1401.512 bs=512 \
count=160
Read error: I/O error
0+0 records in
0+0 records out
# cmp dvd_image.1401.2048 dvd_image.303s.2048
#

The SD-1401 behaves nicely in 2048 Bytes/sector mode, but doesn't
support reading DVDs at 512 Bytes/sector.

To find out wether correctly mastered EFS-DVDs are possible at all, I
wanted to ask that someone who does have a DVD-ROM not listed above,
especially one of the Toshiba drives SGI sells, please try to put a
DVD in your drive and try the two or three commands listed above (dd
bs=512, dd bs=2048, cmp img1 img2). At my department we only have
CD-ROM drives installed with the SGIs because DVD-ROM makes little
sense when all installation media is CD and everything else takes
place over the network, but I really hate all the media changing
involved in some cases.

Thank you for your time,
Thomas Jahns
--
"Computers are good at following instructions,
but not at reading your mind."
D. E. Knuth, The TeXbook, Addison-Wesley 1984, 1986, 1996, p. 9