In order to support jumbo frames on OpenIndiana while not having dedicated physical interfaces for iSCSI/NFS/CIFS traffic, you need to raise MTU on physical interfaces to 9000 and reduce it on vnics lying on top of them which are for non-iSCSI/NFS/CIFS traffic.
If you try to do it with dladm:
# dladm set-linkprop -p mtu=1500 pub.408
dladm: warning: cannot set link property 'mtu' on 'pub.408': operation not supported
ipadm to the rescue!
# ipadm set-ifprop -p mtu=1500 -m ipv4 pub.408