dd, potential bug when writing to tape drive?

[Jason Foat]

Hi,

I think I've found a bug in dd, or at the very least 
I'm having trouble using it to write to my tape drive. 

In particular, I'm attempting to use a combination of ssh/dump/dd 
to back up remote systems to a tape drive on my local linuxbox. 
I'm using dd 4.1 with Linux 7.2, on an i686 architecture. For example,

#ssh LINUXBOX /sbin/dump -0 -f -  /dev/sda2 | dd of=/dev/nst0

yields the following sequence:

  DUMP: Date of this level 0 dump: Thu May 16 21:03:40 2002
  DUMP: Dumping /dev/sda2 (/) to standard output
  DUMP: Exclude ext3 journal inode 8
  DUMP: Label: /
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 10472849 tape blocks.
  DUMP: Volume 1 started with block 1 at: Thu May 16 21:03:53 2002
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 2.40% done at 837 kB/s, finished in 3:23
  DUMP: 4.84% done at 844 kB/s, finished in 3:16
  DUMP: 7.24% done at 842 kB/s, finished in 3:12
  DUMP: 9.64% done at 841 kB/s, finished in 3:07
  DUMP: 12.03% done at 839 kB/s, finished in 3:02
  DUMP: 14.41% done at 838 kB/s, finished in 2:58
dd: writing `/dev/nst0': Invalid argument
3156720+41 records in
3156740+0 records out

Note the 'Invalid argument' error that comes up 15% of 
the way through the dump.

I can also generate a similar error by attempting to 
write a simple file to the tape:

# echo `date` | dd of=/dev/nst0

yields

dd: writing `/dev/nst0': Invalid argument
0+1 records in
0+0 records out

For a truley bizaare twist to this, if I issue a simliar 
dump command to a SOLARISBOX, the dump completes just fine. 

Is this a bug, or am I doing something wrong?

Thanks,

Jason Foat