Hi Jeroen,

As quoted from Jeroen Heijungs <Jeroen.Heijungs AT Het-Muziektheater DOT nl>:
> what exactly are the differences between the different levels of
> backup?

A level N backup includes all files modified since the last level M
backup where M < N.  So a level 1 backup includes all files changed
since the last level 0 backup; a level 2 backup includes all files
changed since the last level 1 backup (or if there was no such backup,
it includes all files changed since the last level 0 backup), etc.
A level 0 backup includes all files, period.
See e.g. the manual page for ufsdump for some more information.

> And to be sure:
> - at least once per dumpcycle there is a fullbackup

Amanda tries to do that, yes.  You will get a warning if you are near
the end of your tape cycle and a level 0 dump of a file system hasn't
been made thus far.
["Last full dump of %s:%s on tape %s overwritten in %d run%s."]

> - the other runs are mostly level 1 (incremental),

That depends.  Amanda tries to balance things and if there's enough room
on the tape, it may decide to run a level 0 more than once in the tape
cycle.

> so all changes to the filesystems are on tape - is this right ???

In principle (unless your tape cycle is too short, or you have too much
incremental data to fit even on one tape) all changed files are
somewhere in the tape cycle.

Met vriendelijke groet,
-- 
-- Gertjan van Oosten, gertjan AT West DOT NL, West Consulting B.V., +31 15 
2191 600