All products go through a life cycle that varies in intensity. At the beginning, the pace of change is hectic as engineers strive to add features to build a product that takes market share and wins deals. Over time, the need to add features lessens. Engineers fix bugs, but the product stabilizes into a shape that holds until engineers are ready to release a new generation of the product, at which time the cycle restarts.
Microsoft Exchange 2000 Server is the second generation of Exchange and incorporates a lot of changes from the previous generation (Exchange Server 4.0 through Exchange Server 5.5). The Store is partitioned, a new SMTP routing engine replaces the X.400-based Message Transfer Agent (MTA), and Active Directory (AD) provides directory services. Exchange 2000 Service Pack 1 (SP1) and SP2 refine the product by fixing bugs that appeared during production use and introducing new features such as the Mailbox Manager in SP1 and a rewritten directory access (DSAccess) component in SP2.
In late July 2002, Microsoft released Exchange 2000 SP3 (which you can download from http://www.microsoft.com/exchange/downloads/2000/sp3/default.asp), but don't expect to find many new features. Instead, Microsoft expects SP3 to improve quality and stability by delivering a comprehensive set of fixes accumulated since SP2 went out the door. At the same time, SP3 provides the platform for future upgrades to the next functional release of Exchange (code-named Titanium), expected in mid-2003. You won't be able to upgrade from SP2 or SP1 to Titanium.
Additionally, although Microsoft doesn't support running Exchange 2000 SP3 on a Windows .NET Server (Win.NET Server) 2003 system, SP3 provides some initial support for the first deployments of Win.NET Server by being able to use a Win.NET Server domain controller (DC). However, support for Win.NET Server isn't a high priority for SP3 because Microsoft doesn't expect the new OS to be in widespread use before Titanium ships.
The only visible evidence that you've upgraded a server to SP3 is a new build number. Figure 1, page 40, shows the build number as seen through the Exchange System Manager (ESM) console. Note that the build number of the shipping release is 6249.4, rather than the 6249.1 you see in the figure, because Microsoft fixed a couple of last-minute bugs just after I wrote this article. Microsoft thinks of Exchange 2000 as version 6.0. Titanium is known as version 6.5, which indicates that it's an evolutionary upgrade to Exchange rather than the major change that Exchange 2000 marked.
Because SP3 doesn't include any major new features, you might conclude that you can overlook it. However, this view is a little short-sighted because SP3 includes some important security upgrades among its bug fixes. Also, you'll eventually have to deploy SP3 if you want to upgrade a server to Titanium. A review of SP3's contents might help you determine whether deploying the service pack early is a good idea.
Lower Network Demand
The SP2 DSAccess component provides a new set of suitability tests to improve the way that Exchange selects DCs and Global Catalogs (GCs) and streamlines the failover process that occurs when a DC goes offline. SP3 builds on the new platform by reducing the traffic between Exchange and DCs, largely through better caching of configuration data and information about AD objects such as mail-enabled accounts and contacts. SP3 also reduces the number of Lightweight Directory Access Protocol (LDAP) queries made when the routing service validates addresses in message headers.
The impact of these changes varies from network to network. If your servers operate across low-bandwidth links that connect Exchange servers to GCs, you can expect to see fewer outages or delays in message routing caused by loss of connectivity between Exchange and GCs. On the other hand, if you always place Exchange servers in close network proximity to GCs (i.e., the Exchange servers and GCs are on the same LAN segment whenever possible), the SP3 changes have less impact. I always like to see Exchange's network demand driven down because not every company has high-speed LAN-quality connectivity always available.
SP3 also updates DS2MB (the System Attendant component that synchronizes changes made to the Microsoft IIS metabase with the Exchange configuration data held in the AD configuration naming context) so that it makes fewer LDAP calls to the AD. The IIS metabase holds configuration data about many services that Exchange uses, including the protocol stacks (e.g., HTTP, POP3, IMAP4) and SMTP virtual servers. DS2MB ensures that any changes made to the metabase or to AD (through ESM) are synchronized. The need for synchronization might seem strange, but it's a side effect of the way that Exchange now consumes services from IIS rather than implementing its own support for Internet protocols, as Exchange 5.5 does.
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