VMware vSphere 5.5 is really close to its End of Support, that will mean no more updates and possible limited support from VMware.
The End of General Support for vSphere 5.5 is September 19, 2018. To maintain your full level of support and subscription services, VMware recommends upgrading to vSphere 6.5, or to a newer version.
Technical Guidance for vSphere 5.5 will be still available until September 19, 2019 primarily through the self-help portal. During the Technical Guidance phase, VMware does not offer new hardware support, server/client/guest OS updates, new security patches or bug fixes unless otherwise noted. For more information, visit VMware Lifecycle Support Phases.
Note that with version 6.5 U1, VMware has extended the general support for vSphere 6.5 to a full five years from the date of release, which means the general support for vSphere 6.5 will end November 15, 2021. Quite enough, and note that, actually the date it’s the same both for 6.5 and 6.7.
You can remain with an “unsupported” version? Possible but risky, considering the several bugs that are present (like Meltdown, Spectre, Foreshadow, …) where you need also some patches at hypervisor layer.
To be clear, it does not means that the product becomes instantly unsupported. VMware Support will still help in the event of an issue in an environment running these products. There are, however, some serious limitations to how far this goes now that it is outside of General Support. And don’t expect to see new security patches or to see it supported by 3rd party software (maybe yes, but potentially no).
For more information see: What does End of General Support mean?
But at which version should upgrade? All version 6.x have an active general support.
So actually the best choices are to upgrade to version 6.5 (and not to 6.0).
Note that the upgrade path to vSphere 6.7 is possible only from vSphere 6.0 or 6.5… So this could be another reason to upgrade your 5.5 installation in order to be able to perform a future upgrade.
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