Virtual machines host business applications, and these applications, in most cases, have service dependencies. During an HA-initiated restart of such VMs, if such service dependencies are not taken into account, even though the VMs will be restarted, the business applications will not be in a functional state. Services dependencies are time-sensitive, meaning if service-A is dependant on service-D, starting service-A prior to a full startup of service-D may either cause service-A not to start, or to run in a non-functional state. HA will not restart services in a guest OS once the VM has been started.
For instance, if an application is dependent on its database being hosted in a different VM, then it is important to ensure that the database VM and its services start up first, before the application VM is started. In this recipe, we will learn...