Epsilon In NetApp

As we know the basics about Epsilon that it holds the extra vote among the crowd of nodes in a cluster. Epsilon can be defined as the node which has been elected that will be counted as master and provide quorum availability to other nodes.

Each time secondary node gets a heartbeat or a ping from Master which is our Epsilon holding node. The point to be noted here is it sends 13 consecutive heartbeats and if it didn't get any response back from node then it is counted as the OOQ [Out of Quorum]; If the node's RDB among the clusters are not responding on that case node is counted as a sick node.

Now we have talked about the nodes basic concepts that actually will be helpful in understanding the concept of Epsilon transfer procedure.

Then, how epsilon is transferred among the cluster nodes.

1. NetApp, if identify that the node is down then it simply takes the health logs of the mgwd application of that particular node.

2. Now it identifies that which node has SFO [Storage FailOver] enabled.

3. After collecting the knowledge of above required data it then checks on which node all the RDB's are online.

4. After confirming all the pre-requisites, it transfers the Epsilon to the other node.