outcome of big rsync. Puzzling

[mlaks at verizon.net]

Hi,
I just completed a really big rsync described earlier. Ie about 13,945 
directories transfered about 600GB of data.

Of 13,945 directories, 13,9441 directories transfer with matching du -b sizes 
of the preimage to  the size of the destination machine image.
of the 4 remaining directories i found 
source vs destination in bytes
---------
a) 20480  vs          34922496 
b) 28672  vs          24576 
c) 61718528 vs       61714432 
d) 157790208 vs     157786112 

each directory consists of subdirectories of medical images in dicom format.
Most interesting to me was case a) where the preimage was smaller than the 
image!!!!
in fact, when i looked at the data in the directory a) in the destination, 
they seemed to be consistent dicom files. ie they seem to open with dicom 
file parsers. While the preimage directory in the case of a) i actually  has 
no files to be found in the subdirectory. Thats why it is so small.

I should mention that I did once have a problem with this server and I once 
had to run fsck.ext3 on the raid drive to fix some linked files. 

I reran rsync and the result above is a fixed point (does not change on 
resend).

I am amazed at how well rsync seems to work (another large directory went 
through unscathed). Is there any prior experience with this behavior?

Mitchell