I've just realised that you are refering to this drive as "SSHD".
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The SSHD drive is only 20% full
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Is this is a Solid State Drive?
If so then that could explain some of what you are reporting.
Or is this actually a SSHD - a Hybrid Drive? (A HDD with a smaller SSD 'cache' built in).
Indeed that would better explain what you are reporting.
To be sure can you give the make and model of the drive in question?
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SSD
You should not (normally) defrag an SSD.
SSDs work diferently to spinning drives, they generally look after themselves with just the help of an occasional 'Trim' needed.
They spread files all over the place on the drive to increase their lifetime, 'wear leveling'.
If you do defrag an SSD the wear leveling will usually just undo the work again.
'Moving files to the end of the drive' is also meaningless for a SSD, the wear leveling will simply spread them out again.
Windows (or Defraggler) shouldn't normally let you defragment a SSD only 'optimise' (trim) it - but Windows (and so Defraggler) will sometimes incorrectly identify a SSD as a HDD, or vice-versa.
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SSHD
With a Hybrid drive the question of defragging or not becomes more of a grey area.
One problem is that most of the discussion you see about it can be 4 or 5 years old, and the technology changes fast so it may not still be relevant.
It's mainly a HDD so can be defragged, but that will affect the SSD portion and so may impact the performance of the drive overall.
Then there can be the problem of the defragging tool reporting the normal wear leveling of the SSD portion as 'fragmentation'.
(Again that could explain some of what you are seeing/reporting).
It's probably best to refer to the manufacturers website/information for the particular hybrid drive and follow their recommendations regarding whether to defrag it or not.
Personally I'd leave it alone, see below.
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General (Personal Opinion)
Since I've been answering questions here, and so thinking more about what defragmenting is actually doing, I've come to the conclusion that defragmenting is not realy required with todays drives, whether HHD, SSD, or Hybrid.
In fact it's not been <em>necessary</em> for the past 20 years or so, and certainly not since FAT was generally replaced by NTFS.
Yes it's nice to see lots of blue blocks packed together in a drive map display - but if you never looked at a drive map so never saw those blocks then would you notice any difference in your computers performance? I doubt it very much.
"Look our tool can show you a chart that looks untidy, and after moving things about it can show you one that looks tidier"
But has moving things about changed anything performance wise? Nothing that you'd normally notice
Maybe if your drive had had very, very, heavy write/delete/write-new operations and was in a mess, but for most of us I doubt it very much.
You are spending time making a tidy looking drive map simply for the sake of making a tidy looking drive map.
Again that's one reason why Windows no longer shows you a drive map - if you can't see it then it can't bother you.
Moving files to the 'start' of the disc so they can load faster?
Years ago with slow spinning drives (maybe even floppys) and slow CPUs that could be important, these days you won't notice any practical difference.
Defragging is just something that over the years we have all become 'programmed' to do without really thinking about if it's actually needed.
The time you spend doing it is thousands of times more than any time it will save you loading files.
If you still want to do it then fair enough that's your choice.
I see defragging dissapearing altogether in the next few years, at least for home users.
Spinning HDDs are going the way of floppys and it won't be long before we are all using SSDs, except for a few die hards with vintage/vetran setups.
Sorry, that turned out a lot longer than I had intended.