SMI-S(Storage Management Initiative-Spec) facilitates three very basic tasks that almost every SAN Mgmt Software needs to provide :
a) Discovery -> Discovery of SMI-S conformant devices from a SAN mgmt server.
b) Monitoring -> The SMI-S client can gather status about each device like health , fault management checks etc.
c) Control -> An SMI-S client enables an IT administrator to actively manage devices in a SAN. For e.g. LUN masking , LUN mapping provided the client has Access Control to LUN's from those host FC ports.
Apart from this , SMI-s facilitates a lot of other services like Multipathing , Copy Services that provide a standardised way of going about things.This standardisation increases efficiency and productivity for vendors who dont need to write vendor-centric or applications using proprietary protocols anymore .