I've just taken over at a client running an older VMware vSphere version 5.1. I want to upgrade this to 5.5. The installation is running on IBM System x3650 M4 servers, which I have firmware upgraded. Do I need a customized ISO file for this, or can I just download the VMware vCenter Server 5.5 Update 3k and modules ISO from VMware and use this?
Are there any things that I should be aware of or upgrade in a specific order?