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Re: [Bug-xorriso] ISO-Disc not recognized

From: Thomas Schmitt
Subject: Re: [Bug-xorriso] ISO-Disc not recognized
Date: Thu, 04 Jun 2015 09:48:47 +0200


> I have a 50GB BD-RE. [...]
> Now I blanked this disk (-blank fast), wrote it ( streaming mode on ).
> But then the automounter in linux says it cannot mount the udf file
> system on this disk. With
>  udiskctl mount -b /dev/... --filesystem-type iso9660 --options ro
> it mounts it. But the volumename is 'disk' not the name I set when the disc
> was written.

"Blanking" of BD-RE is just a little write operation
which makes invalid an eventual ISO 9660 filesystem on the
medium. This only serves the purpose to let xorriso believe
that the medium may be written from scratch, rather than
an ISO 9660 session should be appended.

"xorriso -as cdrecord" will consider all BD-RE blank and
overwrite them from scratch.

Well, you report of "udf". xorriso in its native mode will
only produce and write ISO 9660. So i assume you first produced
an UDF image file and then used a burn program (like
"xorriso -as cdrecord", growisofs, or cdrecord) to put it
on medium.

>  udiskctl mount -b /dev/... --filesystem-type iso9660 --options ro

But doesn't this mean you have an ISO 9660 on the disc ?

> It seems blank blanks not enough.

It might be that some remaining UDF anchor block at the end
of a previously written UDF filesystem was not overwritten by
the new UDF image. I have few experience with UDF and cannot
tell whether trailing garbage might disturb mountability.
(ISO 9660 has no backup superblocks and thus can stand any
 trailing garbage.)

>  On DVD+RWs I blank them allways with
>  dd if=/dev/zero of=/dev/thedvdwriter bs=32k count=250
> [...] But dd doesn't work on BD-REs it says its a ro device.

A Linux kernel should be willing to write to BD-RE.

Whatever, try to use "xorriso -as cdrecord" instead of dd:

  dd if=/dev/zero bs=32k count=250 | \
    xorriso -as cdrecord -v dev=/dev/thedvdwriter stream_recording=on -

But if my theory of a UDF backup anchor block is true, then you
would have to overwrite it too. Not knowing where exactly it is,
you'd have to zeroize the whole BD-RE:

  blocks=$(xorriso -outdev /dev/thedvdwriter -toc 2>/dev/null | grep '^Media 
blocks' | awk '{print $10}')

  dd if=/dev/zero bs=2048 count=$blocks | xorriso -as cdrecord ...

Have a nice day :)


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