VIOS and Perf Monitoring

I am getting ready to build a system with VIOS as the Hosting OS and will be
running several IBM i partitions. I know I should use several smaller
virtual disks vs 1 big one per partition so the IBM i OS wil see multiple
disks/arms. So lets say I have 4 IBM i Partitions all on top of VIOS. Each
partition will see 8 35GB drives and lets say there are 24 139GB ( or
whatever size VIOS wants to call them ) drives available to VIOS to allocate
disk space with. So lots of room but could use more arms. Now I start a
really disk intensive process on 2 partitions. How can I tell how busy the
drives really are at the VIOS level? On a partition with IBM i hosting I can
do WRKDSKSTS on the base IBM i. Just wondering how to approach disk perf
issues inthe future.

Thanks