Re: Backup.

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

Hi,

peter@easthope.ca wrote:
> >   xorriso -for_backup -dev /dev/sr0 \
> > Finding a file as it existed months or years ago can be tedious

I wrote:
> > You could give the backups volume ids which tell the date.

peter@easthope.ca wrote:
> Thanks.  I should have added that when you mentioned a few
> years ago.

I am working on a solution for your non-unique volume id situation
by optionally referring to modification timestamps.
A new command -toc_info_type can switch -toc away from showing volume ids:

  $ xorriso -indev /dev/sr0  -toc_info_type mtime  -toc
  xorriso 1.5.7 : RockRidge filesystem manipulator, libburnia project.
  ...
  Media current: DVD+RW
  ...
  Volume id    : 'HOME_Z_2024_06_27_225526'
  ...
  TOC layout   : Idx ,  sbsector ,       Size , Modification Time
  ISO session  :   1 ,        32 ,   1240808s , 2024.06.20.232334
  ISO session  :   2 ,   1240864 ,     29797s , 2024.06.21.220651
  ISO session  :   3 ,   1270688 ,     20484s , 2024.06.23.225019
  ISO session  :   4 ,   1291200 ,     28928s , 2024.06.24.224429
  ISO session  :   5 ,   1320128 ,     21352s , 2024.06.25.223943
  ISO session  :   6 ,   1341504 ,     30352s , 2024.06.26.223934
  ISO session  :   7 ,   1371872 ,     29023s , 2024.06.27.225617
  Media summary: 7 sessions, 1400744 data blocks, 2736m data, 1746m free

This is a zisofs compressed backup which happens every evening except
saturdays.
Note the time difference between 2024_06_27_225526 and 2024.06.27.225617.
These 51 seconds where spent between program start and begin of writing.

This program enhancement is already committed to git.
In a few days there will be a new GNU xorriso 1.5.7 tarball, which is
easy to build and to test without any danger of frankendebianing.
I'll give you a note.

Currently i am working on a mount gesture which shall automate the task
of picking the youngest backup before a given time point:

   -mount /dev/sr0 not_after 2024.06.22.120000 /mnt/iso

I think "not_after" is a concise way to say "younger_or_exactly_that_age".
Up to the next release i could take better proposals. :))

(I am having my fun with time zones. The ISO 9660 timestamps can have a
time zone from their maker and the computer running xorriso has a local
time zone. Argh ...)


> >          -assert_volid 'BOB_*' fatal

> Prevents me from appending to a DVD from another backup system. But I
> need to add it when beginning a blank DVD.

You may use it also on a DVD which already has sessions with non-unique
ids. This needs two editing operations in your script.

Begin by adding the volume id command to the backup-of-backup run:

  -volid BOB_"$(date '+%Y_%m_%d_%H%M%S')"

Then do an add-on backup to the DVD with the boring ids.

After this session add the check command:

  -assert_volid 'BOB_*' fatal

In the further backup runs, the DVD is supposed to pass this check.


Have a nice day :)

Thomas