Quick reminder that vSphere 5.5 reaches end-of-life this month – September 19th.
That old workhorse of a platform that many customers are still running for a plethora of reasons is finally reaching end of life. That means no more updates, and no more support from VMware. You will be limited to the self help portal and VMware does not offer new hardware support, server/client/guest OS updates, new security patches or bug fixes.
What are my options?
Quite simple here. You need to upgrade. There is no direct path to the latest and greatest vSphere 6.7, so you will need to upgrade to either 6.0 or 6.5 first.
Even if your 5.5 era hardware will not support vSphere 6.5, I would recommend you at least update vCenter to 6.5 even if you can only uplift your old hardware to ESXi 6.0. Not least so you have access to the beautiful vCenter HTML5 Client. Uplevel vCenter is always compatible with downlevel ESXi.
Further reading: VMware Upgrade Center