Re: Problem with growisofs -- cannot write multisession DVDs without ejecting and reloading tray
Hi,
> > OpenSolaris snv 134 always mounts the youngest session.
> You'll have to forgive me, but I don't know what this means. Would that
> mean that only the last files written can be seen, or all of them?
You see all files which you added (and did not delete later).
The capability to access older states is interesting with
incremental backups.
ISO 9660 multi-session works like this:
The new session adds a new superblock, a new complete directory
tree, and the content of data files which were newly added
or overwritten by the session.
The older superblocks and directory trees still exist on the
disc. They may point to older versions of files which got
replaced by other content in further sessions, and they may
contain files which were deleted from the directory tree
of the younger sessions.
Operating systems by default use the youngest superblock
and directory tree for mounting.
But as said, mounting older sessions imight be desirable with
incremental backups. E.g. if i want to mount the backup state
of three days ago, i put in my backup BD-R and do
xorriso -indev /dev/sr2 -toc
which tells me
TOC layout : Idx , sbsector , Size , Volume Id
ISO session : 1 , 0 , 1461973s , HOME_2015_01_05_130954
ISO session : 2 , 1462144 , 53613s , HOME_2015_01_06_114520
...
ISO session : 126 , 8364224 , 54847s , HOME_2015_05_10_113721
ISO session : 127 , 8419232 , 62170s , HOME_2015_05_11_120517
ISO session : 128 , 8481568 , 63170s , HOME_2015_05_12_135346
Media summary: 128 sessions, 8544896 data blocks, 16.3g data, 7177m free
If i then execute (on Linux)
mount -o sbsector=8364224 /dev/sr2 /mnt/iso
i get to see the backup state of may 10 2015, 11:37:21.
There is some convenience built in. The run
xorriso -mount_cmd /dev/sr2 volid '*_2015_05_10_*' /mnt/iso
on Linux makes this proposal of a mount command:
mount -t iso9660 -o nodev,noexec,nosuid,ro,sbsector=8364224 '/dev/sr2' '/mnt/iso'
On FreeBSD the proposal would rather look like
mount_cd9660 -o noexec,nosuid -s 8364224 '/dev/cd1' '/mnt/iso'
A privileged user may also do
xorriso -osirrox on -mount /dev/sr2 volid '*_2015_05_10_*' /mnt/iso
and have the proposed command executed directly by xorriso.
(One still has to umount manually, when done.)
My backup sessions got their volume ids with time stamp
by xorriso command
-volid HOME_"$(date '+%Y_%m_%d_%H%M%S')"
when the backups were made. (See man page example
"Incremental backup of a few directory trees".)
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