>exclude /data/.snapshot/*
>exclude /data/.snapshot/.../*
>
>The output seems it still backups the /data/.snapshot directory...

Phillip - Take the manual literally as to what it says about Include/Exclude:
          Exclude excludes files - it does *not* exclude directories, meaning
that it will still traverse that area looking for directories to back up.
Follow the manual recommendation and code EXCLUDE.DIR instead, to wholly
exclude the directory.
  Richard Sims, BU