[root@coolkiss ~]#  dump -0u -j -f /backups/myproject.dump  /srv/myproject/
  DUMP: You can't update the dumpdates file when dumping a subdirectory
  DUMP: The ENTIRE dump is aborted.

[root@coolkiss ~]#  dump -0 -j -f /backups/myproject.dump  /srv/myproject/
  DUMP: Date of this level 0 dump: Mon Jan  9 14:37:10 2012
  DUMP: Dumping /dev/hda2 (/ (dir srv/myproject)) to /backups/myproject.dump
  DUMP: Label: /
  DUMP: Writing 10 Kilobyte records
  DUMP: Compressing output at compression level 2 (bzlib)
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 6448 blocks.
  DUMP: Volume 1 started with block 1 at: Mon Jan  9 14:37:11 2012
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: Closing /backups/myproject.dump
  DUMP: Volume 1 completed at: Mon Jan  9 14:37:19 2012
  DUMP: Volume 1 took 0:00:08
  DUMP: Volume 1 transfer rate: 608 kB/s
  DUMP: Volume 1 6580kB uncompressed, 4866kB compressed, 1.353:1
  DUMP: 6580 blocks (6.43MB) on 1 volume(s)
  DUMP: finished in 8 seconds, throughput 822 kBytes/sec
  DUMP: Date of this level 0 dump: Mon Jan  9 14:37:10 2012
  DUMP: Date this dump completed:  Mon Jan  9 14:37:19 2012
  DUMP: Average transfer rate: 608 kB/s
  DUMP: Wrote 6580kB uncompressed, 4866kB compressed, 1.353:1
  DUMP: DUMP IS DONE

当你不是针对整个 partition备份时，不能使用 -u 参数

[root@coolkiss ~]# cp -a  /var/log/  /srv/myproject/

[root@coolkiss ~]#  dump -1 -j -f /backups/myproject.dump.1  /srv/myproject/
  DUMP: Only level 0 dumps are allowed on a subdirectory
  DUMP: The ENTIRE dump is aborted.

子目录的备份只能是0级别的。