What Exchange Server hardware configuration is on your Christmas list? Now that Microsoft has released Exchange 2000 Server and organizations are starting to plan their deployments, the calls for performance and sizing data for Exchange servers are streaming in. We're all trying to find the perfect hardware configuration for Exchange 2000 that will give us the best performance and reliability for the lowest cost. Therefore, let's take a brief two-part look at sizing servers for Exchange 2000. This week, I focus on two key areas: the server role and the processor subsystem. Next week, I'll wrap up with memory subsystem and disk subsystem design for Exchange 2000.

The most important place to start with Exchange 2000 server sizing is to look at the server's role. Like Exchange 5.5, Exchange 2000 servers can have multiple roles that directly affect performance. They can be mailbox servers, public folder servers, bridgehead servers, free/busy servers, and SMTP servers. New to Exchange 2000 are the roles of front-end servers, conferencing servers, and Instant Messaging (IM) servers. Server roles might also be complicated by the relationship they have with the Windows 2000 Active Directory (AD). An Exchange 2000 server that is also a domain controller (DC) or global catalog (GC) server (not a recommended configuration) has greater resource requirements. Your Exchange 2000 server's role directly influences which server subsystem is most heavily affected.

Intel processors change faster than the OSs and applications that run on them (a result of Moore's Law, which I quip as "Intel's need for profit will drive processor technology to double every 18 months"). Exchange 2000 can take advantage of more CPU cycles when they're available. As far as CPU scalability, Microsoft reports that Exchange 2000 can scale to only seven or eight CPUs, thus deflating sales presentations from 32-way systems vendors about scaling up to 32 processors (although, I've seen data showing scalability to 12 processors with a lot of tuning). For Exchange 2000, you're better off taking a "scale-out" strategy (adding more servers instead of bigger ones) and deploying multiple smaller 8-processor systems instead of fewer large 32-processor systems. One alternative is to use Windows 2000 Datacenter's hardware partitioning to carve up those 32-way systems into four 8-way systems. Exchange Server roles and functionality that benefit most from more CPU cycles include bridgehead servers, conferencing servers (running the H.323 and T.120 services), front-end servers, large mailbox servers, and any store server with content indexing turned on. Most deployments I'm involved with are defaulting to 8-processor systems for the majority of their mailbox, public folder, and bridgehead server designs.

Next week, I'll continue my look at the perfect hardware configuration for Exchange 2000 by discussing memory and disk subsystems. In my opinion, these two subsystems are the most crucial to your Exchange server's performance and reliability.