One of the things I like about creating host definitions on XIV, Storwize V7000 or SVC is that for the vast majority of host types, the default choice is the correct choice. This saves me having to specifically tell the storage what operating system each host is running.
However in recent times more and more choices have snuck in. For instance in 126.96.36.199 code the Storwize V7000 and SVC had to add an extra option for OpenVMS hosts (there is an alert related to this here). Fortunately most of these exceptions are (from my perspective) for relatively obscure operating systems (users can start spamming me now).
So you need to warn the XIV if your host is running HP-UX or zVM:
On the SVC or Storwize V7000 you need to change from default if your host is running HP-UX or OpenVMS. There is also TPGS (or Target Port Group Support) for use with Apple OS and Solaris hosts using MPxIO. For more details visit this link for Solaris and this link for Apple.
Why does this requirement exist? Or put differently, why can’t the storage be smart enough to just detect the host OS and save the storage admin this bother? Sadly it all has to do with how the hosts issues and responds to SCSI commands.
HP-UX for instance uses flat space addressing (rather than peripheral device addressing). If the storage does not respond in the expected way it will see only 8 LUNs per port (which is not many). I have seen some strange things when HP-UX hosts have not been defined correctly. I have seen even stranger things when non HP-UX have been defined as HP-UX!
OpenVMS on the other hand gets very upset if the storage reports itself compliant with a SCSI specification higher than SPC2 (which is now a very old SCSI specification).
The good news is that for AIX, Linux, Windows and VMware hosts, default works just fine.