Re: [Bug-xorriso] BDXL support

[Thomas Schmitt]

Hi,

Johan de Jong wrote:
> Paranoid aren't I? ;-)

Not at all. A pile of backup media is a sign of mental health.


> I have attempted to write another disc today
> (still failed to close the first one).

There is no urgent need to close it. Given the possible quality
problems between drive and medium, i would keep it as is, unless
its content is not worth keeping.

If you indeed want to close it, the most simple way is to add
a session with not much change and to set -close to "on" before
writing:

  xorriso \
     -for_backup \
     -dev /dev/sr1 \
     -close on \
     -changes_pending yes \
     -commit_eject all

This will write a new superblock and directory tree. The tree
refers to data file content in the first session. It will
be mounted on Linux by default.
(You may force mounting of the first session by mount(8) option
   -o sbsector=0
)


> It took two attempts as the first failed once again due to an
> (media) error. Unfortunately I failed to save the messages,

Record the messages of your xorriso runs in a log file

  xorriso \
    ...\
    2>&1 | tee -i /tmp/xorriso_log


> but I remember
> that it failed already at the first 32 sectors. Also, there was a message
> that there was a failure to allocate a track of xxxx bytes. 
> [...]
> It seems unlikely that it has anything to do
> with the OS or the software, but rather the drive (firmware perhaps?

Media error is in any case internal to the drive and its relation
to the medium. It may be influenced by choices made by the burn
program, which can cause the impression that a media error depends
on operating system or burn software.
But in best case this demonstrates that the relation between drive
and medium is only half broken.

Failure to reserve a track is supposed to be caused by a medium error
too, if the size would fit on the medium.

It may be that this BD medium is still blank and could work
with another attempt or in another drive.


> I hope the succesrate will increase in the future otherwise this way of
> archiving important date becomes cumbersome and too expensive.

You are in new territory in two ways:
- multi-layer BD usage is still rare
- M-Disc is still an exotic dye technology.

Try multi-layer BD with organic dye.

My own experience with 25 GB BD-R is much better than 50%.
Single session hardly ever fails. Multi-session could work more
reliably.
25 GB BD-RE are quite reliable. The first burns always succeed
but i hade a few which died after only a dozen re-uses.

The prices for 50 GB and 100 GB BD media are not attractive.
Multi-layer BD-RE are not easy to get at all.


Have a nice day :)

Thomas