We have an iSCSI SAN setup with Dell's EqualLogic PS series SANs. SAN HQ reports a 30ms write delay. Is this 30ms for the SAN box itself to write the data to the disks, or does the 30ms also include network time getting the data to the SAN box?
Those metrics only include "in-box" latency, as the SAN has no way of knowing how long packets took to get there from the HBA. To get total latency numbers, you need to grab metrics from the OSes using the SAN.