Unable to make SMB Multichannel work in SCALE

[NickF1227]

@e7balt

As noted in that post, despite what the TrueNAS documentation states, it is possible to get SMB multichannel working with just a single network interface but requires that your NIC supports RSS and that you configure TrueNAS scale using the appropriate smb_options.

I am confused here. The whole point of SMB multichannel, as I understand it, is to increase fault tollerance…ie I had a bad cable… and also to increase throughput. You definitely do not get the fault tollerance from a single interface, and I haven’t seen much in the way of evidence to suggest that you’d actually get performance benefit in doing this. So yes, you can do it, I’m just not sure why you would want to?

For sure, tho I am glad you brought up your client side config. Some client side Windows network-stack tuning is important. https://forums.truenas.com/t/high-speed-windows-client-performance-tuning/

@iX_Resources

In my testing, in this environment, I found the best mix of performance between these two systems was with the following settings. The same settings were applied to both systems.

• Toying around with buffers, it seems that the best speeds I was able to achieve were with 2048 Send and 1024 Receive. Increasing the buffer sizes beyond these values decreased performance for me, but YMMV.

• Jumbo Frames to 9014 did seem to help, but in doing so I have statically increased the number of issues in the TCP stack.

• Interrupt Morderation Disabled made the biggest performance difference.

I found that in my testing, some settings did not properly revert back to defaults when I expected them to. The only way I was able to reset the NICs back to default properly was to uninstall/reinstall them in Device Manager:

Also worth nothing, in my previous testing RSS actually made performance worse.

• Changing RSS settings may have some performance to unlock too, but in my testing so far all of the variations I have tried resulted in performance degradation.