During an implementation of Cisco UCS – one of the vmkernel ports on a standard switch was acting funny – it wasn’t getting set to the desired MTU of 9000. What made it odd is other kernel ports on that same switch were setting themselves correctly. To resolve this – PowerShell to the rescue. A quick search of google lead me to a post by Martijn Smit. His blog post came in very handy as it provided the context of setting MTU for either a port group a vSwitch or a standard switch. In my case I was only worried about setting it on a VMKernel port.
From your vcenter you can capture the appropriate vmk port you need to set. From PowerCLI