FreeLists / openbeosstorage / [openbeosstorage] Re: ISO9660/cdrom progress

["Axel Dörfler" <axeld@xxxxxxxxxxxxxxxx>]

Tyler Dauwalder <tyler@xxxxxxxxxxxxx> wrote:
> > Er, I probably just don't know about multi-session CDs. A CD 
> > doesn't
> > simply consist of sessions, but these sessions are grouped in 
> > volumes=3F=3F
> > If that is so, it should be an information the Disk Device API is 
> > able
> > to provide.
> With iso9660 file systems, you can refer to file data from previous 
> sessions instead of duplicating the same data over again.  So, say 
> you 
> have 20 files that you back up on a CD.  Then a week later, you want 
> to 
> back them up again, but only one of them has changed.  Instead of 
> writing all 20 files again, only the changed file will be written, 
> and 
> the remaining entries will just refer to the data in the previous 
> session. 

Furthermore, you can have different "main" sessions - they all can have 
none or more other sessions on one disk.
I.e. you could burn one basic session, and add to more sessions to that 
disk that both are based on that first one.

> So, I think that it's not really a session add-on thing as much as a 
> file system add-on thing.  With iso9660, I believe all the related 
> volumes have a common "volume set" identifier (I'd need to double 
> check 
> this, though).  We'd probably need something similar to be able to 
> distinquish which volumes are part of a set and which volumes are 
> independent.  We'd probably also need a way to designate the 
> chronological ordering of the volumes;  either a datestamp or an 
> ordinal numbering, I suppose.  I'm nearly done revamping the session 
> module, so I could look into the details of how iso9960 handles 
> things 
> after I finish.  Thoughts=3F      

I really think we should be able to deal with that kind of thing at the 
disk scanner level - we probably should propose something like "this is 
a main partition", and Tracker only shows those by default.

Adios...
   Axel.