Strange drive benchmark - speeding up towards end of drive.

[MustardTiger]

Hi everyone. One of my drives is benchmarking quite differently to the others, and I'm not sure why. The drive in question is a shucked WD drive (WD40EMAZ). I'm not sure whether it's SMR or not, but all my other drives are CMR/PMR.

 

Its SMART status looks fine, although it say's 'TRIM available', so does this means it's an SMR? And could that cause this behaviour of speeding up towards the end of the disk?

 

Many thanks in advance!

 

[JorgeB]

It's normal with some SMR drives, it will show correct speed once the drive is fully written once.

[MustardTiger]

3 minutes ago, JorgeB said:

It's normal with some SMR drives, it will show correct speed once the drive is fully written once.

Ah ok, thank you.  Do you mind elaborating a bit on what you mean by "once the drive is fully written once"? Do you mean once the drive is filled up 100% with data at one time, or as in once each sector has been written to since new? The disk has been powered on for 2+ years total, and is currently about 95% full. 

[JorgeB]

2 minutes ago, chrisjwalker said:

or as in once each sector has been written to since new?

This, any sectors that have never been written are known by the firmware, so the disk returns zeros directly from the controller, it doesn't read the disk surface, hence the higher speeds.

[MustardTiger]

16 hours ago, JorgeB said:

This, any sectors that have never been written are known by the firmware, so the disk returns zeros directly from the controller, it doesn't read the disk surface, hence the higher speeds.

Ok cool, thanks for the explanation, much appreciated!