Estimated time to write 2 * 12288 Mbyte: 26880 sec = 7 h 28 min
    wrote 298832 32Kb blocks in 76 files in 10632 seconds (short write)
    wrote 310628 32Kb blocks in 158 files in 10840 seconds (short write)

These two lines are actually a little strange.  I would have expected
that the second pass wrote a little bit less then the first pass (and
the difference is the space taken up by the additional filemarks).

*shrugs*