FreeNAS transfer speed drops after 30 minutes of uptime

[Pietroos]

A Samsung 860 QVO 1TB drive will NEVER do 1000MB/sec. Nor does SATA-3 support that speed. At best, an 860 QVO does a little over 500MB/sec until its cache fills, after which it drops to around 80MB/sec. That's less than 1/12 of what you seem to be expecting out of this drive.
See the first chart on this page: https://www.tomshardware.com/reviews/samsung-860-qvo-ssd,5920.html

It is a typo error, I meant 100MB/s

 

[Pietroos]

Ok, so this behavior manifests with all disks. It looks like something with the Ethernet controller, then. Which driver are you using? The em or igb drivers? Have you enabled or disabled offload?

Like I said earlier, yes this behavior manifests with all the disks. I don't know exactly wich diver I'm using for the Ethernet controller, I can tell if you can give me the procedure to see it. I'm not aware if the offload is eabled or disabled as well, could you help me on this as well?

 

[Samuel Tai]

Run ifconfig -a, or look at Network->Network Summary. The ifconfig output is better, as the options description will tell you the state of offload as well.

 

[subhuman]

It is a typo error, I meant 100MB/s

And even that it can't sustain after its cache fills. QLC is S-L-O-W for direct writing, slower than most HDDs.
So back to your original assertion, yes I am telling you it cannot sustain 100MB/sec. But it also should not be dropping all the way down to the 1MB/sec you say you're experiencing.

 

[no_connection]

QLC write hole is very unlikely to be relevant here. And if you are limited by Gb network there is no reason it should not sustain it for hours if not indefinitely (to full). Any tests that shows it being pushed to write hole does so with full SATA write for many GB of data before it happens.
Show me any evidence that 100MB continuous write from the start will push it to write hole.
And yes I'm aware it drops below 100MB when it happens.

 

[subhuman]

Show me any evidence that 100MB continuous write from the start will push it to write hole.

I already did. I linked to an article where Tomshardware benchmarked the same model Samsung QVO 1TB and they found its sustained write speed to be 80MB/sec. Last I checked, 80 is less than 100.
Meaning the cache will fill at a rate of 20MB/sec under sustained write. The 860 QVO has a variable size cache, based on how full the drive is. It is a minimum of 6GB, maximum of 42GB. At 20 MB/sec, it will take between 300 and 2100 seconds, or 5 to 35 minutes, to fill. The creator of this thread says it slows down after 30 minutes. This is within the expected range for that drive under these conditions.