When node lost, unexpectedly why StatefulSet pods are rescheduled ?

Issue

• The pods which are deployed through StatefulSet were rescheduled unexpectedly to other available nodes, when the node lost.
• It's an unexpected result on StatefulSet pods.
  • Refer Delete Pods for more details.

Kubernetes (versions 1.5 or newer) will not delete Pods just because a Node is unreachable. 
The Pods running on an unreachable Node enter the ‘Terminating’ or ‘Unknown’ state after a timeout. 
Pods may also enter these states when the user attempts graceful deletion of a Pod on an unreachable Node. 
The only ways in which a Pod in such a state can be removed from the apiserver are as follows:

  * The Node object is deleted (either by you, or by the Node Controller).
  * The kubelet on the unresponsive Node starts responding, kills the Pod and removes the entry from the apiserver.
  * Force deletion of the Pod by the user.