Through the introduction of new server roles, Microsoft Exchange Server 2007 SP1 setup and deployment have been re-engineered to improve the administrative experience. Exchange Server 2007 SP1 provides five distinct server roles that align with the way messaging systems are typically deployed and distributed.

A server role is a unit that logically groups the features and components that are required to perform a specific function in the messaging environment. Each server role includes features that support its function together with related configuration and security settings and a list of predefined tasks for managing and configuring those features.

Exchange 2007 Service Pack 1 (SP1) has a default transport database cache size of 128MB. This size does not allow as much dynamic growth on Hub servers with higher than normal message rates, or when an unexpected load from increased message size comes into a server. To better allow for cache growth, the new guidance is to increase the DatabaseMaxCacheSize value from 128MB to 512MB on Hub servers with 4 GB or more memory installed.

When evaluating how to properly size your Outlook Anywhere deployment and the network utilization requirements for your Exchange 2007 environment, scalability of the Outlook Anywhere feature for Microsoft Exchange Server 2007 becomes important, white paper Outlook Anywhere Scalability with Outlook 2007, Outlook 2003, and Exchange 2007 gives detailed information.

The reference architecture is designed to support a tiered approach to implementation of services. The architecture is designed to support those hosters entering the market with plans to grow their services offers on pace with the growth of the business.

The architecture targets two design points:

• Entry Tier - MAPI subscriber base from 5000 - 20,000
  
• Upper Tier - MAPI subscriber base from 20,000 - 100,000
  

  Note:
  Upper Tier is more designed toward 100,000 concurrent MAPI users, assuming a heavy usage profile.

The solution design defines the number of servers required for each design point with a set of formulas as part of the solution to provide the tools service providers can use to grow their service from one design point to the next.

Note:
Actual MAPI users supported by the system could be significantly higher, depending on the level of concurrency. For example, if in average, 10% concurrent MAPI users are active, the actual Entry Tire architecture can support up to two hundred thousand MAPI users (200,000*10% = 20,000); the Upper Tier architecture can support up to one million MAPI users (1,000,000*10%=100,000).

Note:
Scalability is largely dependent on the protocol mix (for example, the percentage of Outlook Anywhere, Outlook Web Access, POP, IMAP) and the user’s usage profile. The recommendation is based on heavy usage profile.

Note:

In Hosted Messaging and Collaboration version 4.0 and previous versions, we have three design references instead of two. In Hosted Messaging and Collaboration version 4.5, the original Middle Tier is renamed to Entry Tier and the original Entry Tier is removed. This is aimed at higher scale service provider who can reach business profitability by providing reliable services up to 10,000 MAPI mailboxes. Lower end service providers need to understand their differentiated advantage and focus on the real added value – perhaps becoming a white label reseller.