To get the best performance out of VMware’s iSCSI initiator it’s a good idea to enable jumbo frames on the ESX hosts. First configure a new vSwitch dedicated to the iSCSI network and if you’re doing this in the GUI delete the default port group that is created.
Then hop into the command line and type:
- “esxcfg-vswitch -m 9000 vSwitch1” (where vSwitch1 matches the number of your virtual switch)
Now your virtual switch has jumbo frames enabled but we need to add a port group with jumbo frames enabled so enter the following to create the port group and assign an IP address:
- esxcfg-vswitch -A iSCSI vSwitch1
- esxcfg-vmknic -a -i 10.97.1.40 -n 255.255.255.0 -m 9000 iSCSI
Check to make sure 9000 MTU is applied on the switch and port group by running the following:
- esxcfg-vswitch -l
- esxcfg-vmknic -l
And lastly test a large packet by running:
- vmkping 10.97.1.10 -s 9000