Implementing Witness Service for Various Cluster Failover Scenarios

The witness service came as part of cluster enabled SMB3 protocol implementation. For the first time SMB clients have become aware of the server state. They can be notified immediately when the state changes, so they can make their own decision or be suggested where should they reconnect. The information coming from the network subsystem is a natural candidate for the data feed to such service. As network interfaces on the server can be configured and tuned according to the current load and system state, providing some of that information to the clients facilitates in less disruptive experience of client-server connection. Other sources could include monitoring of critical system services or even adminstrator-driven actions. The talk covers the design concepts behind the witness service employing modules realising several different data feeds combined together to provide a better failover experience.

Learning Objectives

Sources of data that can be useful for Witness (and SMB3) clients
Extendable witness service design
Practical experience from implementing some of the modules