Once enabled, VM Monitoring, with the help of the VMware tools that are installed in the VMs, will monitor the heartbeats from the VMs. The intervals are governed by the monitoring sensitivity that is configured for the VM. The default monitoring sensitivity is set to high, in which case, HA expects a heartbeat from the virtual machine every 30 seconds. If the heartbeat is not received, then VM Monitoring will look for any storage or network I/O activity in the past 120 seconds (this is the default das.iostatsInterval value). If there are none, then the VM is reset, and more importantly, it is reset only three times during an hour's reset-time window.