Growth Planning for your Exchange Server Deployments

How are you dealing with the growth of your Exchange Server deployment? Managing an Exchange Server deployment with one server at one location is a lot different than managing 200 or 300 servers spread across the planet. Are you anticipating and planning for growth or just frantically reacting to it?

The first growth-related problem that comes to mind is storage. Of course, we can set quotas for our information stores (ISs) that limit things such as mailbox size or control the size of attachments and items that come through our Message Transfer Agents (MTAs) and Internet gateways, but how do we handle real growth? As your deployment grows, you must deal with several storage concerns. First, as your existing user base accumulates more mail, users will either move the mail to .pst files or ask for more space on the server. If you give them more space on the server (by increasing the maximum limit on their mailboxes), consider what this will do to backup and restore times. For example, on a server supporting 1000 users, each with a 50MB mailbox, the private IS could grow from 50GB to 100GB if you were to increase mailbox size to 100MB per user (using a simplistic calculation). Can you still restore 100GB within your recovery service level agreement (SLA) window? Increasing the number of servers also exacerbates this situation. With everyone on the same server, you get maximum benefit from Exchange’s single-instance storage feature. As the number of servers grows in your deployment, it becomes increasingly difficult to achieve a high single-instance storage ratio because users are less localized to one server, and items must be duplicated throughout the deployment. As the organization grows, allocating users by workgroup on a particular server to achieve a high degree of single-instance storage becomes an impractical design goal. Growth means more users on more servers and larger ISs, which translates into management overhead.

Another problem that growth creates for an Exchange Server deployment is replication traffic. Organizations that are growing rapidly or migrating from other messaging systems to Exchange will feel the heat of replication. As the number of servers within a site grows, the amount of intrasite MTA and directory replication increases. Similar effects occur when the number of sites grows. More servers and more sites means the Exchange directory service and MTA spend more time talking to other servers. Before you add more servers and sites to your deployment, take time to understand the effects the directory, public folder, and free/busy replication will have on the overall environment.

Anticipating the consequences and proactively managing for growth is essential for healthy Exchange Server deployments (and systems administrators). Some key areas to focus on are storage, disaster recovery, replication overhead, and administrative implications of growth. Plan ahead and understand the issues so you can manage growth instead of growth managing you.