After decisions have been made about AD design, Exchange server placement, and client access, optimization of the Exchange server itself helps ensure efficiency, reliability, and security for the messaging platform.

Designing an Optimal Operating System Configuration for Exchange

As previously mentioned, Exchange Server 2007 only operates on the Windows Server 2003 operating system, and is scheduled to be able to run on the next version of the Windows Server operating system, currently referred to as Windows Longhorn. The enhancements to the operating system, especially in regard to security, make Windows Server 2003 the optimal choice for Exchange. Unless clustering (including Cluster Continuous Replication) is required, which is not common for smaller organizations, the Standard Edition of Windows Server 2003 can be installed as the OS.

NOTE Contrary to popular misconception, the Enterprise Edition of Exchange can be installed on the Standard Edition of the operating system, and vice versa. Although there has been a lot of confusion on this concept, both versions of Exchange were designed to interoperate with either version of Windows.

Avoiding Virtual Memory Fragmentation Issues

The previous iterations of Windows Server have suffered from a problem with virtual memory (VM) fragmentation. The problem would manifest itself on systems with greater than 1GB of RAM, which run memory-intensive applications such as SQL Server or Exchange. The Advanced Server Edition of Windows 2000 Server enabled a workaround for this problem, in the form of a memory allocation switch that allocated additional memory for the user kernel.

Windows Server 2003 includes the capability of using this memory optimization technique in both the Standard and the Enterprise Editions of the software, so that the switch can now be used on any Windows Server 2003 system with more than 1GB of physical RAM. The switch is added to the end of the boot.ini file.

The /3GB switch tells Windows to allocate 3GB of memory for the user kernel, and the /USERVA=3030 switch optimizes the memory configuration, based on tests performed by
Microsoft that determined the perfect number of megabytes to allocate for optimal performance and the least likely instance of VM fragmentation. This setting only applies to the 32-bit version of Windows 2003, so it would not apply to Exchange 2007 servers but would apply to 32-bit domain controllers and any other supporting 32-bit servers in an Exchange 2007 environment.

Configuring Disk Options for Performance

The single most important design element, which improves the efficiency and speed of Exchange, is the separation of the Exchange database and the Exchange logs onto a separate hard drive volume. Because of the inherent differences in the type of hard drive operations performed (logs perform primarily write operations, databases primarily read), separating these elements onto separate volumes dramatically increases server performance. Keep these components separate in even the smallest Exchange server implementations.

Working with Multiple Exchange Databases and Storage Groups

The Enterprise Edition of Exchange Server 2007 not only enables databases of larger than 75GB, it also enables the creation of multiple separate databases on a single server. This concept gives great flexibility in design while enabling reduced downtime and increased performance.

A storage group is a logical grouping of databases that share a single set of logs. Each Exchange Server 2007 Enterprise system can handle a maximum of 50 storage groups per server. Each storage group can contain a maximum of five databases each, although the total number of databases on a server cannot equal more than 50.

NOTE If Cluster Continuous Replication (CCR) is to be used, it is important to note that CCR only supports a single database per storage group. Also, Microsoft recommends no more than 30 databases on a server running CCR.

In practice, however, each instance of a storage group that is created uses a greater amount of resources, so it is wise to create additional storage groups only if absolutely necessary. Multiple databases, on the other hand, can solve several problems:

. Reduce database restore time—Smaller databases take less time to restore from tape. This concept can be helpful if there is a group of users who require quicker recovery time (such as management). All mailboxes for this group could then be placed in a separate database to provide quicker recovery time in the event of a server or database failure.

. Provide for separate mailbox limit policies—Each database can be configured with different mailbox storage limits. For example, the standard user database could have a 200-MB limit on mailboxes, and the management database could have a 500MB limit.

. Mitigate risk by distributing user load—By distributing user load across multiple databases, the risk of losing all user mail connectivity is reduced. For example, if a single database failed that contained all users, no one would be able to mail. If those users were divided across three databases, however, only one third of those users would be unable to mail in the event of a database failure.

NOTE

One disadvantage to multiple databases is that the concept of single-instance storage is lost across databases. Single-instance storage occurs when only one copy of an email message sent to multiple people is stored on the server, dramatically reducing the space needed to store mass mailings. Each separate database must keep a copy of mass mailings, however, which increases the aggregate total size of the databases.

Understanding Clustering for Exchange Server 2007

Exchange Server 2007 is configured to use Windows Server 2003 clustering for enhanced redundancy and increased uptime. Clustering is an expensive option, but one that will increase reliability of the Exchange Server 2007 implementation.

Clustering options with Exchange Server 2007 have significantly changed over those available in previous versions. Traditional, shared storage clustering is now referred to as a Single Copy Cluster. New options for clustering databases across geographical locations automatically using asynchronous synchronization of log files is now available and is referred to as Cluster Continuous Replication (CCR).

NOTE Microsoft no longer supports a full active-active clustering configuration. Consequently, at least one cluster node should be configured as passive. With eight-way clustering, for example, this means that seven nodes can be active and one node must be passive.

Monitoring Design Concepts with Microsoft Operations Manager 2005

The enhancements to Exchange Server 2007 do not stop with the improvements to the product itself. New functionality has been added to the Exchange Management Pack for Microsoft Operations Manager (MOM) that enables MOM to monitor Exchange servers for critical events and performance data. The MOM Management Pack is preconfigured to monitor for Exchange-specific information and to enable administrators to proactively monitor Exchange servers.