On 11/1/07, Arno Lehmann <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> 01.11.2007 16:43,, Hydro Meteor wrote::
> > Hello all --
> >
> > I'm not sure how many others have run into this problem, but according
> > to the Bacula User's Guide, there are two ways to "blank" an unformatted
> > (fresh from the spindle) DVD disc (in my case I'm using / testing DVD+RW
> > discs):
> >
> > 1.) Not the entire disc:
> >
> > # dd if=/dev/zero bs=1024 count=512 | growisofs -Z
> /dev/xxx=/dev/fd/0
> >
> >
> >
> > 2.) The entire disc:
> >
> > # growisofs -Z /dev/xxx=/dev/zero
> >
> >
> ...
> > Getting back the aforementioned, what I find a bit strange however is
> > that partially blanking a new DVD+RW out of the box yields error for me,
> > as in (where /dev/cdrom is how Debian, as standard practice, see the
> > mapped SuperDrive on the Xserve):
> ...
> > However, if I formatted an entire DVD+RW disc, I had no problems getting
> > the Storage Daemon to complete a backup job writing to the fully blanked
> > DVD.
>
> Oh god... that is a really difficult question, I think. When I was
> working on the dvd-handler script, I tried lots of things. What you
> see dvd-handler doing is, basically, what I found worked for me.
Sorry to ask a painful question :-) ... but in your answer, I have many
more times appreciation of what you must have gone through (the pain and the
suffering).
I worked with - if I recall correctly - three different DVD writer
> drives, DVD+R, DVD-R, DVD+RW, and DVD-RW. I juggled dozens of
> different disk around, and managed to make some unusable, some
> unreadable by some, but not all my, DVD drives, and so on.
>
> I also read lots and lots of stuff on DVD formats, the differences
> between + and - media, the different ways of formatting, and so on.
>
> In the end, I didn't understand anything :-) ,
heh! I can understand -- there's lots to collect. Also, you probably started
this project before you would have the benefits of community organized
information sources such as Wikipedia, true?
read through my notes,
> and implemented what worked in most of my test cases. For example, I
> found that to effectively blank a DVD for use in one drive, I needed a
> minimum size of data overwritten, while other drives (or the drivers
> handling them) accepted a disk as empty when only the first few
> sectors were blanked.
>
> > Question: how do DVD disc media vendors (TDK, Verbatim, et al) ship DVD
> > media?
>
> I have no idea :-)
>
> There is a difference between an unsed disk and a blanked or a
> formatted one. I don't recall the details now, but "Restricted
> Overwrite" was one example of how you can handle the same type of
> media in different ways...
>
> > I presume that they do not fill the bits on their DVDs with ASCII
> > NULL characters (which is what happens when utilizing the /dev/zero
> > device), true?
>
> I guess you're right there. The actual disk contents is probably
> simply invalid to all the interpretation layers above physical.
>
> If you want to know more, you might try to use the dvd-handler test
> command - I believe it reports an excerpt of the actual disk status.
> Naturally, dvd+rw-mediainfo, which is used by dvd-handler, has much
> more information to print.
Arno and friends, it was the dvd+rw-mediainfo (running in Debian as the
Guest Operating System under Parallels as a virtual machine) that gave me
the info which then gave me hints and clues. For example, I am using
TDK 4.7GB DVD+RW discs. When I rand the dvd+rw-mediainfo after
inserting a new TDK
DVD+RW out of the spindle, I got the following output:
$ dvd+rw-mediainfo /dev/cdrom
>
INQUIRY: [MATSHITA][DVD-R UJ-85J ][FDSA]
> GET [CURRENT] CONFIGURATION:
> Mounted Media: 1Ah, DVD+RW
> Media ID: PHILIPS/041
> Current Write Speed: 4.0x1385=5540KB/s
> Write Speed #0: 4.0x1385=5540KB/s
> Write Speed #1: 2.4x1385=3324KB/s
> Speed Descriptor#0: 01/2295103 [EMAIL PROTECTED]/s [EMAIL PROTECTED]
> =5540KB/s
> Speed Descriptor#1: 01/2295103 [EMAIL PROTECTED]/s [EMAIL PROTECTED]
> =3324KB/s
> READ DVD STRUCTURE[#0h]:
> Media Book Type: 00h, DVD-ROM book [revision 0]
> Legacy lead-out at: 2295104*2KB=4700372992
> READ DISC INFORMATION:
> Disc status: blank
> Number of Sessions: 1
> State of Last Session: empty
> "Next" Track: 1
> Number of Tracks: 1
> READ FORMAT CAPACITIES:
> unformatted: 2295104*2048=4700372992
> 26h(0): 2295104*2048=4700372992
> READ TRACK INFORMATION[#1]:
> Track State: blank
> Track Start Address: 0*2KB
> Free Blocks: 2295104*2KB
> Track Size: 2295104*2KB
> READ CAPACITY: 0*2048=0
>
The output correctly identifies my Apple Xserve's OEM DVD burner (their
"SuperDrive") as being from Matshita (I think a division of Panasonic).
It was in this output that I found a useful hint -- to use a block size of
2048 bytes instead of the typical (and recommended in the Bacula User's
Guide) of 1024 bytes, as the value of the bs= option in the dd command, like
this:
# dd if=/dev/zero bs=2048 count=512 | growisofs -Z /dev/cdrom=/dev/fd/0
>
Whereas 1024 bytes was not working for me (and thus my only resort was to
blank or "nullify" with ASCII NULL characters the entire disc), the command
above worked just perfect and only took about one minute to de-ice, with
this output:
Executing 'builtin_dd if=/dev/fd/0 of=/dev/cdrom obs=32k seek=0'
> 512+0 records in
> 512+0 records out
> 1048576 bytes (1.0 MB) copied:-[ GET EVENT failed with
> SK=5h/ASC=24h/ACQ=00h]: Input/output error
> /dev/cdrom: pre-formatting blank DVD+RW...
> , 0.127611 seconds, 8.2 MB/s
> /dev/cdrom: "Current Write Speed" is 4.1x1352KBps.
> builtin_dd: 512*2KB out @ average 0.8x1352KBps
> /dev/cdrom: flushing cache
> /dev/cdrom: stopping de-icing
> /dev/cdrom: writing lead-out
>
I wonder, does the manufacturer of the DVD+RW media (in this case I think
the TDK brand name is owned by Philips), determine the block size (2048
bytes)? I suppose so. It would be useful to compare to other DVD+RW disc
brands such as Sony, Verbatim, etc.
Thank you for pointing out the useful command-line tool dvd+rw-mediainfo
command (being that I spend more time on Mac OS X and not as much on Linux,
I wasn't familiar with it). I think it would be valuable to add my discovery
to the Bacula DVD Tips web page maintained by Richard Mortimer and would it
also be valuable to incorporate into the Bacula Wiki? Speaking of which (as
I'm cc'ing Richard), would it perhaps not be easier to move the Bacula DVD
Tips web page into the Bacula Wiki (or Richard would you prefer to maintain
that separately)?
Cheers!
-H
Good luck!
>
> Arno
>
> --
> Arno Lehmann
> IT-Service Lehmann
> www.its-lehmann.de
>
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