To answer your questions about forward and backward compatibility of the Host Agents, refer to the latest Release Notes for the version of Unisphere in question.  For instance, since this is the CLARiiON forum and FLARE 30 is the latest for the CX4:   1) From PowerLink, click through the following breadcrumb trail:  Home > Support > Technical Documentation and Advisories > Software ~ T-Z ~ Documentation > Unisphere > Release Notes   2) Select the document listed under: "Unisphere for Block Release Notes"   3) Review the Table: "Navisphere compatibility matrix"   Simply refer to the version of FLARE (starts with 30 and continues as far back as 19) in the appropriate column of the table, and the compatible version(s) of the Host Agent are listed in the adjacent column.
Hi friends, What is the latest Clariion Flare code version and is it the same as the new VNX series flare version. Thanks! 
Clariion Flare version