High Availability And Disaster Recovery For Exchange Servers Through A Mailbox Replication Approach

By Dr. Vas Srinivasan and Bilal Ahmed, Sonasoft

Email is becoming ubiquitous and has become the standard tool for communication in many enterprises, big and small. Microsoft is the dominant player in the messaging platform market through its Exchange Server. Enterprises are clearly choosing the reliability, scalability, and performance of Exchange, combined with the feature-rich Microsoft Outlook and Outlook Web Access clients and built-in collaboration services for workflow and other applications.

Microsoft Clustering enables users to prevent hardware failures by stringing redundant hardware, called nodes, together through a central cluster manager that coordinates load balancing and data activity. Typically, nodes share common storage space and have the capability of picking up load off of a node that goes down due to hardware or software malfunction. There are two types of cluster environments—active/active and active/passive. In the former, every node in the environment is live and capable of processing requests. When one active node goes down, the others simply process more requests as the load is evenly dispersed across the remaining nodes.

In direct contrast to this storage dependency, using a Standby solution through mailbox replication prevents against hardware, software and storage failures. Standby servers are normally installed on unique, usually geographically independent, Exchange Servers which serve as a barrier to failures of any type.