Upgrade VMware VSA 5.1 to 5.5
First Update vSphere Storage Appliance Manager, then Update vCenter Server
First Update vCenter Server then Update vSphere Storage Appliance Manager
The document "vsa_55_install_admin_guide" and the KB VMware Update sequence 2057795 (Example 4) are different.
Moderator note: As this discussion is about a specific product, I've moved it to the correct area - vSphere Storage Appliance.