samsung 960 evo performance drops ?

Olga-SAN

Limp Gawd
Joined
Mar 14, 2011
Messages
302
hi

so i have an issue : current set of a samsung 960 evos (got 4 of them) work in weird way

initially write performance is kind of ok and according to specs

after some time write performance is 1/3 - 1/4 of what it should be

initially i though it's my raid done in the wrong way

but individual drives are behaving in the same way ;(

is ther any way to fix that ?
 

Grimlaking

2[H]4U
Joined
May 9, 2006
Messages
3,250
What are they plugged into, bios levels? Raid settings? any performance diagnostics or is it a gut feel?
 

arestavo

[H]ard|Gawd
Joined
Mar 25, 2013
Messages
1,617
How hot are they getting during writes?

If the 960 evo is anything like the 950 pro and the SM951, they will throttle at a certain temperature to avoid long term damage.

If heat is the issue, passive heat sinks are the cure. I run my 950 pro in an Angelbird expansion card with a passive heatsink and I don't have that problem.
 

Pandur

Limp Gawd
Joined
Apr 4, 2000
Messages
320
I would start with checking temperatures. These drives can throttle hard if they run to hot.
 

Olga-SAN

Limp Gawd
Joined
Mar 14, 2011
Messages
302
guys thanks for your suggestions !!

temperature is ok (they run a little bit hot but opening a case and using huge fan just to cool them down didn't change anything)

it turns out write performance drop is by design - cache gets filled and that's it ;(

http://www.tomshardware.com/reviews/samsung-960-evo-nvme-ssd-review,4802-2.html

https://www.starwindsoftware.com/blog/benchmarking-samsung-nvme-ssd-960-evo-m-2

http://www.storagereview.com/samsung_960_evo_m2_nvme_ssd_review

similar drop in 4k rnd writes over time

thanks again !!
 

Schmeisser

n00b
Joined
Jan 18, 2016
Messages
35
It should, but the problem is that the drives are not designed for that workload. Treat it like an SSD cache with a USB stick behind it.
 

Grimlaking

2[H]4U
Joined
May 9, 2006
Messages
3,250
under pulsating i/o - yes for sure

under heavy hammer i/o - never ;(

I'm speaking here from perception not experience.

In order to max out the cache and sustain it you would have to have sustained copies that were in effect faster than the controller could sustain writing the cache data to the storage. So in essence... it would have to be at a speed and sustained rate beyond what a consumer would see short of doing a ram drive write to disk when rebooting or shutting down. Right?
 
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