We were looking at the Isilion and HDP support matrix at the following site https://community.emc.com/docs/DOC-37101
For Isilion 8.1.2 we do not see any compatibility with HDP 3.1. We only see the compatibility matrix fro HDP 3.0.1.
Even for Ambari version 2.7.3 that comes with HDP 3.1 looks like note mentioned in the above link.
If someone can clarify it will help
Thanks & Regards,