I tested restoring a Drupal website by
having backuppc generate a tar file, uploading the file to the server and
then extracting the tar file to the new Drupal directory structure. A
large number of files were not restored because a number of Drupal sub-directories
are read-only. Errors included 'Cannot open: Permission denied' and
'Cannot open: No such file or directory'.
I found a reference to the '--delay-directory-restore'
option at http://www.gnu.org/software/tar/manual/tar.html#SEC77
that solved this problem.