Hi,
spin-hi stats in 7-mode systems are a 'false' counter, as they don't usually have anything going on that has meaning to the head.
spin-hi stats are the sum total of all disk-bound workload generated by the cluster side of a CDOT deployment for a particular node.
you will USUALLY see spin-hi latency go up when there is resource contention on the physical side of the node, and that latency will usually translate directly into protocol level latency (which is not always available via atp for cluster systems).
when attempting to asses a cluster, use the spin-hi data to judge if the customer/application facing side of the storage system may be experiencing a performance hit.
Regards,
Jorge