Why is HD Tune benchmark irregular over the used space?

WD External Drives External Drives for PC
1

When it was empty, the graph showed the normal downward curve you can see on the right, for the entirety of the disk. As I’ve written it half full, the used space became this irregular graph. Can anyone explain why? It’s not supposed to matter what kind of files are there, if any, for this benchmark.

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WD Elements 4TB USB3, tried different cables, host controllers, Windows 10 Pro normal and safe mode, all the same. The chart remains the same pattern when re-done.

2

I would suspect the likely reason is the 4TB Elements is an SMR drive and not a PMR drive. Data is stored differently on a SMR drive compared to a PMR.

I know 100% for sure my 4TB My Passport Ultra is an SMR drive … and assume my 4TB Elements as most likely the same.

3

So does your graph look similar? Why would it affect it in this particular way?

4

I don’t usually run benchmarking software ever … but anyways i tested 3 of my WD Portables for you to have a look at.
All Tested on the same USB3.0 input via PCI Epress Card on my PC … From Left to Right … 2TB Elements(455GB Free) > 4TB Elements (15GB Free) > 4TB My Passport Ultra (25GB Free)

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5

Thank you for running them, they look interesting. The 4TB Elements still looks better than mine but it’s not that dissimilar. Out of curiosity I’m doing a type of defrag that actually rearranges everything on the disk (by name or access date), to see if it’s the files themselves that affect the graph pattern, or the mere fact that it’s not empty.

6

All 3 of my drives have never been defragged.

7

That’s okay, it’s not fragmented either, all the data I have on it was a backup in the past days. Just want to physically move them around to see if the files themselves affect/define the repeatable pattern or not.

BTW Windows has a default scheduled background defragmenter, have you disabled that?

8

Yep