On the community forums someone asked if it was possible to influence the HA/FDM master election. (For those who don’t know, FDM is the engineering name for vSphere HA.) Let me state first that I wouldn’t recommend doing this, but there actually is a way to make it very likely a certain host becomes the HA master. In this case this customer wanted to influence the outcome of the election as hosts are distributed across rooms and one host is less likely to fail than others due to power layout etc.
The setting is:
The explanation provided is:
When a master election is held, the FDMs exchange a goodness value, and the FDM with the largest goodness value is elected master. Ties are broken using the host IDs assigned by vCenter Server. This parameter can be used to override the computed goodness value for a given FDM. To force a specific host to be elected master each time an election is held and the host is active, set this option to a large positive value. This option should not be specified at the cluster level.
You can set this by manually editing the following file on the host where you want to increase the chances of winning the election:
More details about this can be found in this KB, which also lists many other advanced options.