The solution presented in this document is designed to simulate a very large number of mailboxes hosted on highly redundant hardware. Application level redundancy is augmented with redundant storage to create a highly available and fault tolerant solution.
The Mailbox Resiliency features of Exchange 2010 have greatly enhanced the availability of Exchange 2010, while also improving I/O performance. The solution presented here is a Mailbox Resiliency solution using two Database Availability Groups (DAGs) and 2 copies of every database. The tested environment simulates all users in these DAGs running on a single Storage Center of the 2 Storage Center configurations, as in a failover event.
The number of users simulated was 50,000 across 10 servers, (5 servers per DAG), with 5,000 users per server. The mailbox size was 2GB per user. Each server has 5 databases, with one copy local and the second copy replicated to a second server on a second Storage Center. This provides redundancy through hardware and software.
The replication mechanism is the native Exchange 2010 DAG log shipping engine. This is a very efficient and reliable replication mechanism and is the recommended method for providing highly-available and redundant Exchange solutions.