Re: write only storage.

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

Hi,

Andrew M.A. Cater wrote:
> > Write only storage - DVD-R or equivalent Blu-Ray

Tim Woodall wrote:
> I already do that but currently that means I have roughly one month of
> backups on network accessible storage before I write to disc.

I do a daily incremental backup on BD-R (plus three on BD-RE and one
on DVD+RW).
All my burners can write at least 128 sessions to BD-R. My ASUS BW-16D1HT
does more than 230.
I hope to reach a new record in a few weeks with my current 11 o'clock
BD-R:

Drive type   : vendor 'ASUS' product 'BW-16D1HT' revision '1.01'
...
Media current: BD-R sequential recording
Media product: CMCMAG/BA5/0 , CMC Magnetics Corporation
Media status : is written , is appendable
Media blocks : 8843072 readable , 3376320 writable , 12219392 overall
ISO offers   : Rock_Ridge
ISO loaded   : Rock_Ridge
TOC layout   : Idx ,  sbsector ,       Size , Volume Id
ISO session  :   1 ,         0 ,   1992263s , HOME_2021_03_02_110936
ISO session  :   2 ,   1992416 ,     33546s , HOME_2021_03_03_110514
ISO session  :   3 ,   2026112 ,     34060s , HOME_2021_03_04_111021
...
ISO session  : 203 ,   8802368 ,     19349s , HOME_2021_09_20_121951
ISO session  : 204 ,   8821888 ,     21020s , HOME_2021_09_21_123308
Media summary: 204 sessions, 8843072 data blocks, 16.9g data, 6594m free

The backup is done essentially according to man xorriso example
"Incremental backup of a few directory trees"
with more -update_r commands and some -not_paths commands.
Linux mounts by default the youngest state. But by help of mount(8)
option -o sbsector= and the numbers in the "sbsector" column it is
possible to mount older states. (With -o loop you may even mount more
than one and compare them.)

DVD+R can take 153 sessions.
DVD-R can theoretically take 99 sessions, but there is substantial waste
space between them. So many sessions means few payload.


Have a nice day :)

Thomas