Personally I wouldn't believe either.
I tend to agree with the 3rd party utility that the drive does not need to be defragged, but only because I see little need to defrag today's drives in today's OSes.
Today's systems and drives are much better at data management and the era of constantly or regularly defragging hard drives has long gone. I have had my Windows 7 system, (three separate 1 TB drives), for over two years and have never needed to consider defragmentation. In fact I haven't even checked the drives for that.
Windows own Defragmenter will advise that a disk needs defragmenting above a certain level of fragmentation. I believe that is 4% fragmentation. But that is easily reached if data is often read to and deleted from drives, but 4% is small and other defragmenter utilities may put the level higher. But in any case I see that Windows 7 runs defragmenting as part of a background process if the system is idle, so it is constantly doing this anyway.
There are myths about defragmenting, such as it makes seek and locate data quicker, but even if that is true, the benefit that we the user would see is minimal if at all.
As a test I ran a Google search for " Is defragmenting really necessary? ". it's a loaded question of course for a Google search, but the number of hits against defragmenting are interesting.
I have windows 7. I got a brand new external USB 2 Terabyte drive for backing up.
After I backed up about 50 gigs I ran defrag analysis. It said I need to defrag the drive.
I got a 3rd party defrag utility and it says the drive does not need to be defraged.
So which program is right?
Are these super large hard drive more sensitive to defragmentation than the smaller drives?
I am a little confused which defrag program to believe.
Please help me figure this out.