Hi all,

I am just committing some changes which should allow Coda to handle
multilevel backups. It has only been tested as far as ...it compiles...
so don't put this on your production servers just yet.

The code has kept backward compatibility reasonably well. The only
gotcha's are, an old backup server will do the incrementals at level 16,
which only matters if backups are mixed with other backup mechanisms
like volutil dump, which does level 1 incrementals.

The new servers also write their `ancient' files in such a way that a
forward server upgrade is transparent, but to switch back the
/vice/backup/*.ancient files will need to be removed (forcing a full
dump on all volumes on the next backup).

Volutil has been extended with an extra `level' option on the
incremental flag.
    volutil dump [-i [<level>]] volume file

Backup has been taught to read from the dumplist, the levelnumber 0-9 in
addition to F (level 0) and I (level 1).

So what used to be:
    7F00049C        IFIIIII         vmm:s.usr

Can now also be specified as:
    7F00049C        1011111         vmm:s.usr

And for the people who want to make life interesting, here is a possible
(about) monthly backup cycle:
    7F00049C        0325476132547613254761325476         vmm:s.usr

Oh yes, the cycle doesn't have to be 7 days, I just figured that one
out while adding the multilevel stuff.

What's left to do? I'd like to add a volutil function to ask the server
for size estimates at the different dumplevels. And at some point
interface to other backups systems like Amanda, so people can choose
their main backup mechanism.

Jan