When installing the Unisphere host agent on a server with multiple IP addresses, the address used for registration with the array is arbitrarily chosen. This can cause issues with communications with the array and seems to be significantly worse when using FC0E. In recent experiences I found that my server, SUSE Linux, would register as an initiator and not a host.
There doesn’t actually appear to be any specific documentation on this with Unisphere though there are lingering Navisphere documents out there. What I eventually found that confirmed what I needed was this document on Deploying Oracle Database 11g on EMC Unified Storage.
The solution: Create a file on / named agentID.txt with exactly two lines of text, the first being the FQDN of the host and the second line of the IP address. Remember, Linux is case sensitive so the file must really be named “agentID.txt”. Once the file has been completed restart hostagent. A restart immediately resolved the issue and my host registered successfully.
Configuration of the host agent on Windows is similar though the path for the agent ID file will obviously be different.