Starting with Qlik Sense June 2017 you can set a RIM node to be a failover candidate for the Central node. That timeout for failover is set automatically to 10 minutes, but you can change that.
Using the QRS API to do so is the recommended way to accomplish this.
Regarding how to call QRS API using Postman, please refer to QRS API using Xrfkey header in Postman
1. First use the following command:
In order to retrieve the service cluster settings
You will need the id returned here in order to make to alter the timeout setting through the /qrs/servicecluster/ endpoint.
In this example, the id is: 2cc76c42-e0a1-4bf6-b818-ed4a10bc6824
2. Send the following API call to alter the timeout:
Content-type: application/jsonRequest body
Copy the response retrieved in step 1 and replace the value for the timeout
Replace the value with the value desired.
You will also need to remove the "[" and the "]" at the beginning and the end of the body.
If the request succeeds, the following response should be returned and from the QMC cluster settings tab you will see that the value has changed: