BE 3600 Upgrading: CASO first? or MMS?

Hello,

I am preparing to upgrading my 2 appliances: 1 CASO and 1 MMS, which one should I deal with first? CASO or MMS?

And anything I should back up beforehand, e.g. the whole Catalog directory, any job settings, etc.?

After the upgrade, do I need to perform on the appliance, i.e. Dedeplication disk,  the action "Inventory and Cataloging"?

Thanks,
Joe