fidefrag doesn't improve file fragmentation

[Kamil Páral]

FiDefrag 2.11, Ubuntu 8.04.

I have just used fidefrag:

$ fidefrag -a .

=== Analyzing . - 1,4G - 8 Files ===

=== Building File List...
=== Building Extended File Info...
          8 / 8 - 100%
 495.86 MB 1382 P 2.79 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 344.23 MB 6631 P 19.26 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 492.43 MB 19911 P 40.43 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi

$ fidefrag -d .

=== Defragmenting . - 1,4G - 8 Files - 5 Passes ===

=== Building File List...

--- Pass 1 / 5 ---

 495.86 MB 1382 P 2.79 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 --> No improvement after defrag: 1382.00 P --> 8040.00 P
 344.23 MB 6631 P 19.26 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 --> Improved: 6631.00 P --> 1280.00 P
 492.43 MB 19911 P 40.43 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi
 --> Improved: 19911.00 P --> 4560.00 P

--- Pass 2 / 5 ---

 495.86 MB 8040 P 16.21 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 --> No improvement after defrag: 8040.00 P --> 8427.00 P
 344.23 MB 1280 P 3.72 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 --> No improvement after defrag: 1280.00 P --> 6469.00 P
 492.43 MB 4560 P 9.26 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi
 --> Improved: 4560.00 P --> 1350.00 P

--- Pass 3 / 5 ---

 495.86 MB 8427 P 16.99 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 --> Improved: 8427.00 P --> 6756.00 P
 344.23 MB 6469 P 18.79 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 --> No improvement after defrag: 6469.00 P --> 6825.00 P
 492.43 MB 1350 P 2.74 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi
 --> No improvement after defrag: 1350.00 P --> 8170.00 P

--- Pass 4 / 5 ---

 495.86 MB 6756 P 13.62 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 --> Improved: 6756.00 P --> 1347.00 P
 344.23 MB 6825 P 19.83 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 --> Improved: 6825.00 P --> 4508.00 P
 492.43 MB 8170 P 16.59 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi
 --> No improvement after defrag: 8170.00 P --> 8259.00 P

--- Pass 5 / 5 ---

 495.86 MB 1347 P 2.72 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 --> No improvement after defrag: 1347.00 P --> 8290.00 P
 344.23 MB 4508 P 13.10 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 --> Improved: 4508.00 P --> 1275.00 P
 492.43 MB 8259 P 16.77 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi
 --> Improved: 8259.00 P --> 4018.00 P

=== DEFRAG OPERATION COMPLETE.

$ fidefrag -a .

=== Analyzing . - 1,4G - 8 Files ===

=== Building File List...
=== Building Extended File Info...
          8 / 8 - 100%
 495.86 MB 8290 P 16.72 P/MB ./The Power Of Nightmares - 02... Phantom Victory.avi
 344.23 MB 1275 P 3.70 P/MB ./The Power Of Nightmares - 01...Its Cold Outside.avi
 492.43 MB 4018 P 8.16 P/MB ./The Power Of Nightmares - 03...dows In The Cave.avi

Look at the first file. Before it has 1382 parts. Now it has 8290 parts. That is clearly not an improvement. When I see this line:
--> No improvement after defrag: 1382.00 P --> 8040.00 P
I expect that the better variant (1382 P) was kept. But fidefrag uses the last variant (8040 P), even though it's much worse. Therefore after running fidefrag the fragmentation can ironically be much worse than before.