I tried to execute a dladm set-linkprop command on a Nexenta RSF-1 HA cluster and received a "link busy" error. Took a minute for me to remember that the Solaris family requires you to unplumb and interface before you administer its persistent properties.
The example below shows how to change the MTU settings using plumb and dladm commands. This allows the RSF-1 controlled interfaces and VIPs to use jumbo frames.
ifconfig ixgbe1 unplumb ifconfig ixgbe0 unplumb dladm set-linkprop -p mtu=9000 ixgbe0 dladm set-linkprop -p mtu=9000 ixgbe1 ifconfig ixgbe0 plumb ifconfig ixgbe1 plumb