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.
** Disclaimer: This article contains references to the words master and/or slave. I recognize these as exclusionary words. The words are used in this article for consistency because it’s currently the words that appear in the software, in the UI, and in the log files. When the software is updated to remove the words, this article will be updated to be in alignment. **
I thought there was a bias towards the host which connected to the most DSs.
I wanted to check with the KB but I can not connect right now 🙁
Duncan Epping says
Yes there is, but in most clusters (hopefully) this is equal
this is cool, we can elect a master of our choice without an election based on resources available. will try editing my config file and have a look on it. Thanks