Enabling jumbo frames for VMs

[bruor]

I'm using truenas scale 23.10.0.1 installed on bare metal.

I've created a bridge and attached it to the physical nic, IP configuration for the instance is applied to the bridge. I have an ubuntu VM running that hosts my docker containers.

I have enabled jumbo frames on the host nic, br0, and VM interfaces. However, I've found that jumbos will only work between the VM and Truenas instance if I also modify the MTU on the vnet1 interface using the "ip" command. Is there a proper way to configure the MTU for this interface within the gui? If not, what is the proper way for me to make this change persistent across reboots?

 

[bruor]

I think I managed to find where I need to set this up.

Managing Init/Shutdown Scripts

Provides information on adding or modifying init/shutdown scripts in TrueNAS SCALE.

www.truenas.com

 

[bruor]

Never mind, after a reboot it looks like the interface for VMs change to vnet0 and had the same MTU as the bridge.

 

[Kailee71]

Out of interest, did it make any difference in iperf or SMB performance? I've found over the years it's no longer necessary to mess around with IP settings to get essentially max achievable performance, regardless of OS/Platform/Virtual or not. Would be nice to see some before/after numbers if it did make a difference.

 

[bruor]

My use case is NFS/iSCSI.

I don't expect a massive difference, just the extra ~5% throughput boost because there is less header data in the packets.