Burning and mounting written BDs

[Kjetil Kjernsmo]

Hi all! 

Thanks for all the efforts you've put into this over the years!

The main thing I'm using my Blu-Ray burner for these days is an annual backup 
of the last year's important data to M-Discs, marketed to last a long time. 
I've done this for some years, and I have mostly used k3b, but since it failed 
on one disc last year, I decided to try xorriso this year. This is on a 
headless Debian box anyway, so command line is better.

The process looked just fine:

kjetil@robin:~/scratch/backup-2023$ xorriso -outdev /dev/sr0 -blank as_needed 
-map ./pooh.kjernsmo.net/ /pooh.kjernsmo.net -map ./kanga.kjernsmo.net/ /
kanga.kjernsmo.net -map ./owl.kjernsmo.net/ /owl.kjernsmo.net -map ./
robin.kjernsmo.net/ /robin.kjernsmo.net -map ./felles/Film/ /Film -map ./
felles/familie.tar.gz.gpg /familie.tar.gz.gpg
xorriso 1.5.4 : RockRidge filesystem manipulator, libburnia project.

Drive current: -outdev '/dev/sr0'
Media current: BD-R sequential recording
Media status : is blank
Media summary: 0 sessions, 0 data blocks, 0 data, 46.6g free
xorriso : NOTE : -blank as_needed: no need for action detected
xorriso : UPDATE :   20400 files added in 1 seconds
xorriso : UPDATE :   24009 files added in 1 seconds
Added to ISO image: directory '/pooh.kjernsmo.net'='/home/kjetil/scratch/
backup-2023/pooh.kjernsmo.net'
xorriso : UPDATE :    3064 files added in 1 seconds
Added to ISO image: directory '/kanga.kjernsmo.net'='/home/kjetil/scratch/
backup-2023/kanga.kjernsmo.net'
xorriso : UPDATE :    5122 files added in 1 seconds
Added to ISO image: directory '/owl.kjernsmo.net'='/home/kjetil/scratch/
backup-2023/owl.kjernsmo.net'
xorriso : UPDATE :    7745 files added in 1 seconds
Added to ISO image: directory '/robin.kjernsmo.net'='/home/kjetil/scratch/
backup-2023/robin.kjernsmo.net'
xorriso : UPDATE :     169 files added in 1 seconds
Added to ISO image: directory '/Film'='/home/kjetil/scratch/backup-2023/
felles/Film'
xorriso : UPDATE :       1 files added in 1 seconds
Added to ISO image: file '/familie.tar.gz.gpg'='/home/kjetil/scratch/
backup-2023/felles/familie.tar.gz.gpg'
xorriso : UPDATE : Thank you for being patient. Working since 0 seconds.
xorriso : UPDATE : Thank you for being patient. Working since 1 seconds.
[ snip ]
xorriso : UPDATE : Closing track/session. Working since 2387 seconds
ISO image produced: 23090263 sectors
Written to medium : 23090432 sectors at LBA 0
Writing to '/dev/sr0' completed successfully.

found medium: ( "/dev/sr0" ) 
=====================================================
DiskInfo: 
Mediatype:        "BD-R Sequential (SRM)" 
Current Profile:  "BD-R Sequential (SRM)" 
Disk state:       incomplete 
Empty:            false 
Rewritable:       false 
Appendable:       true 
Sessions:         1 

Tracks:           1 
Layers:           1 
Capacity:         "5430:50:34"  (LBA  24438784 ) ( 50050629632  Bytes) 
Remaining size:   "299:38:02"  (LBA  1348352 ) ( 2761424896  Bytes) 
Used Size:        "5131:12:32"  (LBA  23090432 ) ( 47289204736  Bytes) 

=====================================================

I tried first to mount it with the usual means, then discovered that xorriso 
could tell me how, so, next thing I tried was this:

root@robin:/dev# mount -t iso9660 -o nodev,noexec,nosuid,ro,sbsector=0 '/dev/
sr0' '/mnt/test/'
mount: /mnt/test: wrong fs type, bad option, bad superblock on /dev/sr0, 
missing codepage or helper program, or other error.
       dmesg(1) may have more information after failed mount system call.

dmesg says:
[4683501.642523] isofs_fill_super: bread failed, dev=sr0, iso_blknum=16, 
block=16

I also tried:

root@robin:/dev# xorriso -dev /dev/sr0 -mount indev auto auto /mnt/test/
xorriso 1.5.4 : RockRidge filesystem manipulator, libburnia project.

xorriso : NOTE : Loading ISO image tree from LBA 0
[ snip ]
xorriso : UPDATE :   40115 nodes read in 9 seconds
Drive current: -dev '/dev/sr0'
Media current: BD-R sequential recording
Media status : is written , is appendable
Media summary: 1 session, 23090432 data blocks, 44.0g data, 2634m free
Volume id    : 'ISOIMAGE'
xorriso : FAILURE : -mount: image-to-disk features are not enabled by option -
osirrox
xorriso : aborting : -abort_on 'FAILURE' encountered 'FAILURE'

dmesg doesn't seem to have an opinion here :-) 

This is on brand new media, and M-discs are really expensive, so they ought to 
be top-of-the-line... And the price makes me reluctant to resort to too much 
trial-and-error too.

Anyone have any idea here?

Kind regards,

Kjetil