In last week's Exchange UPDATE, I talked about server and site consolidation and mentioned that Windows Server 2003, Exchange Server 2003, and Outlook 2003 work together to create significant possibilities for site consolidation. To better understand how you can improve site utilization through consolidation, let's look at some of these products' new features.
Microsoft engineers products to work well together (hence the "better together" motto), and deploying these three products together creates significant synergies. Although Exchange 2003 can run on Windows 2000 Server, some of Exchange 2003's most compelling features depend on the new OS. Furthermore, Exchange 2003's site-consolidation benefits depend to a great extent on OS-level features.
For example, clustering in Windows 2003 is hugely improved over the corresponding functionality in Win2K. You can now build four- and eight-node clusters without using the Datacenter edition, and the new /USERVA parameter provides a great deal of flexibility in configuring RAM usage on machines with more than 1GB of RAM. As a bonus, new support for IP Security (IPSec) security associations in clusters means that you can use IPSec to secure front-end/back-end communications without imposing an extra 5-minute delay on cluster failovers. Clustering might not seem to have much to do with consolidation, but it lets you put more users on clustered mailbox servers to increase both storage and server utilization. You don't need to cluster to achieve effective site consolidation, but the data from Microsoft's internal deployments and early adopters indicate that active/passive clustering can help. Consider Microsoft's deployment: In each cluster, the company uses five identical servers (four active, one passive) plus two smaller auxiliary servers for performing backups. The smaller servers can accept some user load, but that isn't their primary purpose. This architecture, backed by a beefy Storage Area Network (SAN), supports about 4000 users per active node, or 16,000 users per cluster. That's a consolidation success story.
Of course, clustering alone isn't sufficient to drive site consolidation. Windows 2003's Remote Procedure Call (RPC) subsystem also provides several key improvements that support consolidation. (The RPC channel that Exchange and Outlook use is part of the Windows infrastructure.) In Windows 2003, the RPC subsystem can compress or shape RPCs (i.e., arrange the contents of RPC packets) to make best use of the available bandwidth. This ability improves network efficiency on the server, which is key to effective consolidation. Of course, Windows 2003 also provides the ability to tunnel RPC packets over HTTP--an ability that provides a terrific user experience for roaming or mobile users.
Now, on to Outlook. Cached mode is the default for Outlook 2003 for an excellent reason: This mode effectively insulates users from momentary (or longer) network interruptions. As a happy side effect, cached mode reduces the amount of work that the server must do. The Outlook client includes a component that consolidates requests from various Outlook threads and services (e.g., the address book, the mail downloader) whenever possible. Doing so reduces the overall number of connections that the server must deal with.
The future for site consolidation looks good. Microsoft isn't saying just yet what its recommendations are, mostly because it's still gathering data from its (and others') deployments to find out what ratios and sizes are reasonable. However, the basic improvements in Windows 2003's and Exchange 2003's manageability, maintainability, scalability, and security all contribute to your ability to consolidate. Expect to hear a lot more about consolidation at TechEd in Dallas next week; if you get a chance, drop by my session (SEC306, "New Security Features in Exchange 2003") and say hello!