2.5 What needs to be managed?

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What is involved in managing Exchange, and how large an operations staff is needed? In small companies, a small number of people may have responsibility for multiple areas, whereas in large corporations, many people may have roles with narrow sets of responsibilities. Often, these people are from separate organizations.

Regardless of the number of people used to manage Exchange or the size of the organization, specific types of management activities must be performed. Examining a typical Exchange implementation helps identify the areas where management must be performed.

• Exchange organization. An Exchange organization is a hierarchical collection of Exchange routing groups, administrative groups, and servers. The complete collection of Exchange components is known as the organization. The Exchange organization consists of one or more routing groups and one or more administrative groups. An Exchange routing group contains one or more Exchange servers. The servers within an Exchange routing group are connected by a high-bandwidth permanent network connection. (You can use slower network connections between routing groups in your Exchange organization but not within a routing group.) The number of routing groups, administrative groups, and servers required in an enterprise depends on several factors, including the number of users, the number of corporate locations, the network bandwidth between locations, the availability of local IT support staff, and corporate politics. Two enterprises with exactly the same number of users may have an entirely different Exchange organization topology because of differences in network bandwidth, number of locations, or IT group organization.

  Someone must monitor and manage the Exchange organization. This includes monitoring message transfer between Exchange routing groups, between Exchange and other internal e-mail environments, and between Exchange and external e-mail environments such as the Internet. As Exchange servers are added to or removed from the organization, someone must ensure the integrity of the overall e-mail environment.

• Exchange servers, services, and queues. The individual Exchange servers are the most obvious component in the Exchange environment, and the Exchange server software must be functioning properly for the e-mail environment to be in good working order. The Exchange server is not a single, monolithic program. It consists of a cooperating set of services and queues. A message sent using a Messaging Application Programming Interface client is first delivered to the Exchange information store. The information store searches the directory to determine where the message should be delivered. The message is then passed to the message transfer agent, which delivers the message. Anomalies with these services or queues are an immediate indication of a problem with the e-mail environment. These services and queues must be closely monitored.

• Information store. The Exchange information store consists of a public information store and a private information store. The private information store contains all messages in the user's server-based e-mail folders. The public information store contains all objects in the public folders. The key management responsibility regarding the information store is to ensure that the data will not be lost if a hardware error causes the loss of a disk drive. This is typically done through regularly scheduled backups and planned recovery exercises.

• Client software and users. Users are the ones who will ultimately decide whether the e-mail environment is functioning properly. Users do not see the Exchange software. Instead, the user's view of the e-mail environment is through client software such as Outlook. When a client application sends a message, the Exchange server is responsible for routing the message to its intended recipients. The client application also allows users to access the messages in their mailbox. An end-user- oriented help desk is a key operational component of the Exchange e-mail system.

Exchange does not exist in isolation. There are other applications in the network environment, and other processes coexist on Exchange servers-even on 'dedicated' Exchange servers. We must understand the interrelationships between these processes to manage a reliable Exchange infrastructure and to achieve the service levels that departments and business units demand.

We need a clear understanding of the services and components of the Exchange-based e-mail environment. In particular, we need to understand the services and components on which Exchange relies. Proper functioning of an enterprise-wide Exchange environment relies on proper functioning of many components, including the following:

• Windows server software. The Exchange server runs on Windows 2003. Windows failures will have an immediate impact on the Exchange server software. One of the key Windows components is the Active Directory. Before Exchange 2000, Exchange had its own directory. However, Exchange 2000 and Exchange 2003 use the Active Directory services that come with Windows. The Windows Active Directory contains information about Windows objects, including all Exchange objects. This includes complete information about Exchange routing groups, administrative groups, servers, connectors, recipients, public folders, users, mailboxes, and distribution lists. Active Directory replicates this directory information to other Windows domain controllers throughout the organization. It is important to remember that Exchange cannot be administered independently of Windows. Because both Windows and Exchange use the Active Directory, the way you choose to organize your Windows topology may dictate how you administer Exchange.

• Server hardware. Exchange server software cannot run if the underlying hardware fails. You can use RAID arrays, clusters, and other fault-tolerant mechanisms to improve the availability of Exchange servers.

• Domain Name System. This network service enables processes to locate other systems and processes in the network.

• Windows domain environment. Exchange depends on Active Directory to validate user credentials and to provide directory services.

• TCP/IP and the physical network. E-mail systems are networked applications and cannot survive if the underlying network protocols or physical connections fail.

• Client/server connections. The network connection between each user's desktop and the Exchange server must be working properly to have a properly functioning e-mail environment.

• Global Catalog Servers and Domain Controllers. Exchange is dependent on these two services. It is not enough to simply have these services available; the Global Catalog Servers and Domain Controllers must respond quickly to Exchange lookup requests. Slow response will directly affect the Exchange environment.

Correct functioning of an Exchange-based e-mail environment requires all of these components to be in good working order. On thorough investigation, many 'Exchange' problems are found to really be problems with the components on which the e-mail system relies.

If users expect you to provide a reliable Exchange-based messaging infrastructure with a high level of service, you must first ensure that the other components provide similar or greater levels of service. There is a direct negative impact on the level of service provided by Exchange if any of these components fail to deliver the necessary service levels.

Unfortunately, users typically do not understand these dependencies. Users only see the application they are trying to run. If the physical network fails when a user happens to be using Outlook, that user will consider it an e-mail failure. For example, one Exchange performance problem was investigated for many weeks before the cause of the problem was finally identified as a patch cable connecting the Exchange server to a switch. The cable ran too close to the data center's air conditioning unit and uninterruptible power supply, causing interference that forced network retries. Moving the cable fixed the 'Exchange' problem, but not before the perception of Exchange and Outlook was seriously damaged in the user community.

It is unlikely that the group managing the Exchange environment also will have management responsibility for all of the component areas on which Exchange depends. Instead, the Exchange management group should have an agreement with each of the departments responsible for managing these other components. These SLAs should provide a commitment to deliver an agreed on service level that will support the Exchange service level requirements.

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