Exchange 2000 SP1 on Datacenter

The release of Microsoft Exchange 2000 Server's first service pack, which Microsoft scheduled to release in June 2001, provides a more significant feature than just minor bug fixes. In Exchange 2000 Enterprise Server Service Pack 1 (SP1), Microsoft will deliver Windows 2000 Datacenter Server support for Exchange 2000. Last fall, Microsoft shipped Datacenter, which offers the promise of a total solution for data center deployment of Microsoft OSs and applications. The release of Datacenter support for Exchange 2000 raises two questions: How does Exchange 2000 leverage Datacenter, and will this ability really make a difference in your organization's mission-critical deployments?

What's in a Name?
When Microsoft shipped Win2K in December 1999, the company promised that it would later deliver a data center version of Win2K that would raise the bar for the OS. To do so, this data center version was to provide features and support that Microsoft intended to rival mainframe and UNIX environments.

Datacenter is the first Microsoft product that is available solely through OEMs. Vendors such as Compaq, Hewlett-Packard (HP), and Dell offer specific Datacenter product configurations that have been tested on a higher level of compatibility and reliability than the traditional Windows testing process. Each OEM's product must pass rigorous 14-day load and compatibility testing that pushes each hardware configuration to its limit.

Datacenter also offers improved support services. Microsoft requires each OEM to host a support team in which Microsoft and the OEM's engineers work together to provide support. This setup delivers an OS and hardware bundle that's closely tied to joint support programs between Microsoft and the OEM.

So how is Datacenter different from Win2K Server and Win2K Advanced Server? Datacenter's improved testing process and support are differentiating factors, but Datacenter also includes five key features that aren't available in the other Win2K server editions:

1. Support for 32-way SMP systems—Win2K AS provides support for only 8-way SMP systems. Datacenter's support for 32 processors lets CPU-intensive applications scale well, and these applications will benefit tremendously from the additional CPU power.
2. Support for as much as 64GB of physical memory—Through Datacenter's Physical Address Extension (PAE) architecture and the Address Windowing Extensions (AWE) API, applications can access as much as 64GB of RAM.
3. Support for process control objects—Process control objects provide an API that lets developers permit operators and operation rules that are running the system to dynamically tune applications and services.
4. Support for Winsock Direct—Winsock Direct is another new API available in Datacenter that lets applications leverage high-speed interconnects or System Area Networks (SANs) to facilitate interprocess communication or remote procedure calls (RPCs).
5. Support for 4-node clustering—Four-node clustering is one of the most touted advantages of Datacenter over Win2K AS, which supports only 2-node clusters.

Microsoft designed each of these Datacenter features to let Win2K scale beyond its current limitations and enter the data center arena as a platform of choice.

Exchange 2000 on Datacenter
When deploying Exchange 2000 Enterprise Server on Datacenter, you must upgrade to Exchange 2000 Enterprise Server SP1 to garner full support from Microsoft. How well does Exchange 2000 Enterprise Server SP1 leverage each of Datacenter's key features?

Support for 32-way SMP. Microsoft and OEMs have tested Exchange 2000 Enterprise Server SP1, and it will run on a Datacenter-certified 32-way SMP system. (For more information about Datacenter certification, see Microsoft's Web site at http://www.microsoft.com/windows2000/upgrade/compat/certified.asp.) However, initial testing indicates that Exchange 2000 scales well only to a maximum of 8 processors on most implementations. By using process control objects and processor affinity to tune an implementation, some OEMs have been able to scale Exchange 2000 to as many as 12 processors. Therefore, SP1 doesn't help you take advantage of Datacenter's ability to scale to 32 CPUs because SP1 doesn't change Exchange 2000's inability to scale well past 8 CPUs.

OEMs plan to recommend hardware partitioning (another Datacenter feature) to their customers who want to scale Exchange 2000 to systems with more than eight processors. Based on Exchange 2000's constraints and Return on Investment (ROI), I recommend a scale-out rather than a scale-up strategy—one 32-processor system is more expensive than four 8-processor systems. The best way to achieve the lowest total cost of ownership (TCO) with Exchange 2000 is to deploy multiple 8-processor systems (i.e., scaling out) as opposed to fewer 32-processor systems (i.e., scaling up).

Support for as much as 64GB of RAM. Exchange 2000 Enterprise Server SP1 will run on PAE-enabled machines. However, Exchange 2000 doesn't make any calls to the AWE APIs to utilize virtual memory beyond a 4GB address space.

Duplicating Exchange 2000 behavior on Win2K AS, Exchange 2000 Enterprise Server SP1 on a Datacenter system can use the /3GB switch in boot.ini to allocate 3GB of RAM for Exchange application use and 1GB for the OS. (This feature was first available in Exchange Server 5.5 running on Windows NT 4.0, Enterprise Edition.) However, by default, Exchange 2000 won't use more than about 1GB unless you make registry setting changes because Exchange 2000's STORE database cache will allocate only 900MB—less than Exchange Server 5.5, which could allocate almost the entire 3GB for application use. I recommend using the /3GB PAE switch for all Exchange Server systems that have 1GB or more of RAM. This switch simply extends the application process address space to 3GB from Win2K's and NT's 2GB default setting. This switch also reduces the OS's address space to 1GB.