Completing pre-upgrade checks are a crucial part of having a successful upgrade of NSX.
Prechecks are built into the main upgrade bundle, .mub.
Broadcom also provide a dynamic pre-upgrade checks bundle, .pub. This may be updated with known issues outside the cycle of the main software releases.
Prechecks comprise of warnings which will allow the upgrade to proceed and errors which will block an upgrade.
Prechecks should always be run at least 10 days in advance of a planned upgrade activity. This will allow time to address issues without impact on the scheduled activity.
There is no functional impact of running prechecks.
The standalone upgrade evaluation tool is longer required, this functionality was built into NSX from versions 3.2.2 and 4.0.1.1.