Re: Linux M-Disc support

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Paul von Behren wrote:
> Media current: BD-R sequential recording
> Media product: MILLEN/MR1/0 , Millenniata Inc.
> Media status : is blank
> Media blocks : 0 readable , 12219392 writable , 12219392 overall

This one should work with xorriso.


> Media current: BD-R sequential recording, Pseudo Overwrite formatted
> Media product: VERBAT/IMk/0 , Mitsubishi Kagaku Media Co.
> Media status : is unsuitable , is POW formatted
> Media blocks : 35185280 readable , 12906880 unused , 48092160 overall
> Media summary: unsuitable Pseudo Overwrite formatted BD-R

A "100 GB" medium. Must have cost nearly as much as the drive. :))

This one might still be writable by growisofs for an add-on session
with option -M.
Inquire its state by

  dvd+rw-mediainfo /dev/sr0

(The tray with the BD must already be loaded, because dvd+rw-mediainfo
won't pull it in.)

Specs for BD media offer a mode called Pseudo Overwrite where the Defect
Management is (mis-)used to replace written blocks by spare blocks if a
write operation happens again to such a written block.
growisofs uses it to update the superblock at offset 0, whereas libburn
programs rely on the convention that the operating systems mount the
superblock of the first track of the most recent session.


> I will try to burn an m-disk next with xorriso and let you know how it
> goes.

If you use the blank BD-R unformatted, then it will be written with full
nominal speed. That might become loud. Inquire the speeds by

  xorriso -outdev /dev/sr0 -list_speeds

and consider to reduce speed and noise by xorriso command -speed.


If you want Defect Management (of which i'm not overly convinced), then
let xorriso format the medium. You can do this in a separate run before
the actual write run

  xorriso -outdev /dev/sr0 -format "as_needed"

or use the -format command in the course of the first xorriso write run
which uses this medium.

"as_needed" applies the default formatting size (normally 23098 MiB).
You may get proposals for the loaded medium by:

  xorriso -outdev /dev/sr0 -list_formats

like

  Format status: unformatted, up to 23866.0 MiB
  Format idx 0 : 00h , 11826176s , 23098.0 MiB
  Format idx 1 : 32h , 11826176s , 23098.0 MiB
  Format idx 2 : 32h , 5796864s , 11322.0 MiB
  Format idx 3 : 32h , 12088320s , 23610.0 MiB

and choose other division between payload and spare blocks, by e.g.

  xorriso -outdev /dev/sr0 -format by_index_3

  xorriso -outdev /dev/sr0 -format by_size=22586m

(More than 23866m will not be achievable, of course.)


Have a nice day :)

Thomas