Hi,
that's a Warning, not an Error. It's there to inform you what actually happened. If you don't wan't to see these warnings any longer, consult OB2NOREMOTEWARNINGS in your respective DA's .omnirc. But suppressing them doesn't change the fact: When you back up some Unix file system object housing any mount points, these will be entered into the target object as empty directories and may miss their original attributes (because these are invisible due to the root directory attributes of the file system mounted there taking over). The warning is there to make you aware that - should you somehow manage to not back up the mounted file system individually to another target object - your backup will miss it. So check wether you have objects for these clients specifying a source of /var in addition to those sourced by / and if so, all is well. Otherwise, fix your Trees and/or Excludes.
BTW, at least on Linux, you can easily get the true permissions and other attributes of the mount point directory by simply singling out the containing file system in a bind mount. DP's DA makes no use of this, though, and it wouldn't be portable anyway.
HTH;
Andre.