Chapter 3: Understanding Core Exchange Server 2007 Design Plans


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The "heavy" client of Outlook, Outlook 2007, has gone through a significant number of changes, both to the look and feel of the application, and to the back-end mail functionality. The look and feel has been streamlined based on Microsoft research and customer feedback. Users of Outlook 2003 might be familiar with most of the layout, whereas users of Outlook 2000 and previous versions might take some getting used to the layout and configuration.

On the back end, Outlook 2007 improves the MAPI compression that takes place between an Exchange Server 2007 system and the Outlook 2007 client. The increased compression helps reduce network traffic and improve the overall speed of communications between client and server.

In addition to MAPI compression, Outlook 2007 expands upon the Outlook 2003 ability to run in cached mode, which automatically detects slow connections between client and server and adjusts Outlook functionality to match the speed of the link. When a slow link is detected, Outlook can be configured to download only email header information. When emails are opened, the entire email is downloaded, including attachments if necessary. This drastically reduces the amount of bits across the wire that is sent because only those emails that are required are sent across the connection.

The Outlook 2007 client is the most effective and full-functioning client for users who are physically located close to an Exchange server. With the enhancements in cached mode functionality, however, Outlook 2007 can also be effectively used in remote locations. When making the decision about which client to deploy as part of a design, you should keep these concepts in mind.

Accessing Exchange with Outlook Web Access (OWA)

The Outlook Web Access (OWA) client in Exchange Server 2007 has been enhanced and optimized for performance and usability. There is now very little difference between the full function client and OWA. With this in mind, OWA is now an even more efficient client for remote access to the Exchange server. The one major piece of functionality that OWA does not have, but the full Outlook 2007 client does, is offline mail access support. If this is required, the full client should be deployed.

Using Exchange ActiveSync (EAS)

Exchange ActiveSync (EAS) support in Exchange Server 2007 allows a mobile client, such as a Pocket PC device, to synchronize with the Exchange server, allowing for access to email from a handheld device. EAS also supports Direct Push technology, which allows for instantaneous email delivery to handheld devices running Windows Mobile 5.0 and the Messaging Security and Feature Pack (MSFP).

Understanding the Simple Mail Transport Protocol (SMTP)

The Simple Mail Transfer Protocol (SMTP) is an industry-standard protocol that is widely used across the Internet for mail delivery. SMTP is built in to Exchange servers and is used by Exchange systems for relaying mail messages from one system to another, which is similar to the way that mail is relayed across SMTP servers on the Internet. Exchange is dependent on SMTP for mail delivery and uses it for internal and external mail access.

By default, Exchange Server 2007 uses DNS to route messages destined for the Internet out of the Exchange topology. If, however, a user wants to forward messages to a smarthost before they are transmitted to the Internet, an SMTP connector can be manually set up to enable mail relay out of the Exchange system. SMTP connectors also reduce the risk and load on an Exchange server by off-loading the DNS lookup tasks to the SMTP smarthost. SMTP connectors can be specifically designed in an environment for this type of functionality.

Using Outlook Anywhere (Previously Known as RPC over HTTP)

One very effective and improved client access method to Exchange Server 2007 is known as Outlook Anywhere. This technology was previously referred to as RPC over HTTP(s) or Outlook over HTTP(s). This technology enables standard Outlook 2007 access across firewalls. The Outlook 2007 client encapsulates Outlook RPC packets into HTTP or HTTPS packets and sends them across standard web ports (80 and 443), where they are then extracted by the Exchange Server 2007 system. This technology enables Outlook to communicate using its standard RPC protocol, but across firewalls and routers that normally do not allow RPC traffic. The potential uses of this protocol are significant because many situations do not require the use of cumbersome VPN clients.

Configuring Exchange Server 2007 for Maximum Performance and Reliability

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. Figure 3.3 illustrates some examples of how the database and log volumes can be configured.

Figure 3.3


Database and log volume configuration.

On Server1, the OS and logs are located on the same mirrored C:\ volume and the database is located on a separate RAID-5 drive set. With Server2, the configuration is taken up a notch, with the OS only on C:\, the logs on D:\, and the database on the RAID-5 E:\ volume. Finally, Server3 is configured in the optimal configuration, with separate volumes for each database and a volume for the log files. The more advanced a configuration, the more detailed and complex the drive configuration can get. However, the most important factor that must be remembered is to separate the Exchange database from the logs wherever possible.

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 500-MB 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). More information on clustering with Exchange 2007 can be found in Chapters 4, "Architecting an Enterprise-Level Exchange Environment," and 31, "Continuous Backups, Clustering, and Network Load Balancing in Exchange Server 2007."

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. For more information on using MOM to monitor Exchange Server 2007, see Chapter 20, "Using Microsoft Operations Manager to Monitor Exchange Server 2007."

Securing and Maintaining an Exchange Server 2007 Implementation

One of the greatest advantages of Exchange Server 2007 is its emphasis on security. Along with Windows Server 2003, Exchange Server 2007 was developed during and after the Microsoft Trustworthy Computing initiative, which effectively put a greater emphasis on security over new features in the products. In Exchange Server 2007, this means that the OS and the application were designed with services "Secure by Default."

With Secure by Default, all nonessential functionality in Exchange must be turned on if needed. This is a complete change from the previous Microsoft model, which had all services, add-ons, and options turned on and running at all times, presenting much larger security vulnerabilities than was necessary. Designing security effectively becomes much easier in Exchange Server 2007 because it now becomes necessary only to identify components to turn on, as opposed to identifying everything that needs to be turned off.

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