Slow write speeds over 10Gb

[MikeyG]

@artlessknave I assume you have compression turned off on the dataset you are writing those files to?

If so, not sure what's going for the disparity between read/write speeds. Would need more info.

 

[phil1c]

Hey, maybe something I can help with:
I'm going through the reverse problem right now (writes faster than reads) but perhaps these suggestions will help you as well:
1) Jumbo frames (MTU 9000): make sure both machine's NICs are set to using an MTU of 9000. This opened up a bit of performance for me.
2) When performing a file copy between the two machines (both directions), run "top -aSH" from the FreeNAS WebUI shell and keep an eye on "smbd" when it shows up. If it is pegging one core at 100%, you might be CPU limited (apparently smbd is a processor hungry pain at 10gb speeds)
3) Make sure, in your FreeNAS BIOS, that any settings related to CPU performance are set to max, especially if the previous testing shows a pegged CPU core. You might also benefit from turning off hyperthreading.

I hope any of that helps as it did for me. I am, however, running FreeNAS 11.3-RC1 so you're mileage may vary.

 

[artlessknave]

compression turned off

nope, that's with compression on, which makes the zeros read faster even weirder, since you'd that think would be...compressed. I might try again on a no compression dataset (would have to make one), but i dont expect much difference really.

 

[MikeyG]

@artlessknave For that specific test, compression should make a huge difference. On my NAS, with compression on, it looks like it's writing at 7GBps or something impossible. For all 0s, you are basically testing the CPU, and not using the drives at all.

 

[isternbu]

I upgraded my FreeNAS system to a newer, lower power motherboard/CPU and more recent version of FreeNAS. That seemed to fix the problem.

X10SDV-4C-TLN2F Xeon D-1521
64GB DDR4
FreeNAS 11.2-U7

Getting around 800 MB/s now with Windows File Explorer Copy and 500 MB/s with TeraCopy