#183 Strange behavior of UltraDefrag v6.0.1 when sequentially executed on the same volume.

Vladimir Shatilo

Hi to all!

Thanks a lot for UltraDefrag, this is a really great tool.
But some bugs are as usual in place :).

v5.1.2 and v6.0.1 are working pretty strange in "full optimization" mode,
especially v6.0.1. Each time i'll run full optimization it will sequentially
move big sequences of data blocks from beginning of data partition to end and
after that will move data blocks back to their previous place.
That is especially strange that i can run full optimization 2,3 or 5 times on
the same partition and ultradefrag will time to time move the same already
optimized previously blocks of data from beginning to end and back again.
This is pretty confusing and hard to look at when volume size is 500 Gb or more.

Each time after optimization ultradefrag v6.0.1 puts
"Optimized, 2 passes needed" phrase in status column of just optimized drive.
v5.1.2 never did such a way, and past 5.x.x versions never did.

"Quick optimization" works better but after first run on the same partition
it still moves some data blocks to the end of partition and then back again,
data blocks are always the same but not big in size. Behavior the same after
2-nd, 3-rd or 5-th run, it always moves some small sequences of data first to
the end of partition and then back on their previous place, sequences of data
blocks time to time are always the same.

I faced this behavior on different systems with default after installation
parameters (on fresh system). NTFS file system, WinXP and Win7.


  • Stefan Pendl
    Stefan Pendl

    v5.x.x didn't sort in any way, v6.x.x now sorts by path when optimizing with the default settings.

    In addition optimization is now taking all filters into account and has an additional filter to skip files bigger than 20MB by default.

    Thanks for the feedback, we will see how we can improve the algorithm.


  • Stefan Pendl
    Stefan Pendl

    • status: unread --> open
  • MarkEd


    I've already searched for this in the internet and user manual but I couldn't find answer.

    What does the message "3 passes needed" mean?

    Thank you

  • This behavior is caused rather by design than by bugs.

    • status: open --> closed