Jumbo Frames on your vSphere ESXi box

Continuing on from this http://sigtar.com/2010/02/04/vsphere-and-multipathing-iscsi/

you may want to implement jumbo frames to your iSCSI backend…

Enable jumbo frames on your iSCSI target and switches then complete the following on the ESXi hosts (iSCSI initiators)…

This to list your current switch details and port group names…

esxcfg-vswitch -l

The following to allow jumbo frames onto your vswtich (insert your vSwich in following)

esxcfg-vswtich -m 9000 vSwitch0

Then create your kernel port groups that you want to use for iscsi, my commands looked like this… (repeat for each iscsi kernel port you have) — note : DO NOT ADD ANY VMKERNEL(s) from the GUI, instead use the steps below

esxcfg-vswitch -A iSCSI vSwitch0

If you are using a tagged vlan you will also need to add the vlan tag to the above port group

esxcfg-vswitch -v 192 -p iSCSI vSwitch0

esxcfg-vmknic -a iSCSI -i -n -m 9000

To confirm you have set the MTU (frame size) correctely, run the following….

esxcfg-vmknic -l

you should see your iSCSI kernel ports with a MTU of 9000 all going well. Confirm connectivity using

vmkping –s 9000