Microsoft KB Archive/821833

= Exchange cluster resource dependencies in Exchange Server 2003 =

Article ID: 821833

Article Last Modified on 10/25/2007

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APPLIES TO


 * Microsoft Exchange Server 2003 Enterprise Edition
 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Exchange 2000 Server Standard Edition

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SUMMARY
This informational article discusses the changes that have been made to the resource dependency tree in Exchange Server 2003 and how this change can speed cluster shutdowns.



MORE INFORMATION
In an Exchange 2000 cluster, a new cluster group must be created to house the Exchange virtual server. To successfully create a Microsoft Exchange System Attendant resource, the following items must exist in the group:
 * Physical disk resource
 * IP address
 * Network name

When the System Attendant resource is created, these Exchange resources will be automatically created. During the creation process a dependency tree is created.

Exchange 2000 Resource Dependency Tree
The Exchange 2000 resource dependency tree is shown here:    ________________ |               |    |                |    | IP Address     | |               |    |________________|            ^            |            |     ________________         ____________________    |                |       |                    |    |                |       |                    |    | Network Name   |       | Physical Disk(s)| |               |       |                    |    |________________|       |____________________|                ^                     ^                |                     |                 |                     |             ____________________________            |                            |            |                            |            |     System Attendant       | |                           |             |____________________________|             ^             ^              ^            |             |              |            |             |              |               _________   ___________________   _____    |         | |                   | |     |     |         | |                   | |     |                        | Routing | | Information Store | | MTA | | Engine | |                   | |     | |_________| |___________________| |_____|                ^     ^       ^    ^                  |     |       |    |                  |     |       |    |             ___________________________________        |           |       |       |       |       | MS Search | POP3  | SMTP  | IMAP4 | |___________|_______|_______|_______|

Note that the information store resource has five dependencies:
 * SMTP (Simple Mail Transfer Protocol)
 * HTTP
 * POP3 (Post Office Protocol version 3)
 * IMAP4 (Internet Message Access Protocol, Version 4rev1)
 * MSSearch

The message transfer agent (MTA) and routing engine resources are directly dependent on the System Attendant. If a failover occurs, all the resources that have a dependency must go offline before the resource that the resource depends on can try to go offline.

In the scenario that is described in this article, the SMTP resource, the HTTP resource, the IMAP4 resource, the POP3 resource, and the MSSearch resource must be offline before the information store resource can try to go offline. The MTA and routing engine resources can try to go offline immediately because these resources do not have any resources that depend on them.

In Exchange 2000 clusters, the SMTP resource and the information store resource frequently take the longest time to go offline or come online. Frequently, this delay occurs because of large SMTP queues or because large databases require more time to mount or dismount. This delay can lead to longer failover times while the information store resource waits for the SMTP resource before it can try to go offline or come online.

Exchange Server 2003 Resource Dependency Tree
In Exchange Server 2003, the resource dependency tree has been modified so that all Exchange Server 2003 cluster resources are now directly dependent on the System Attendant resource. The Exchange Server 2003 dependency tree is shown here:         ________________ |               |    |                |    | IP Address     | |               |    |________________|            ^            |            |     ________________         ____________________    |                |       |                    |    |                |       |                    |    | Network Name   |       | Physical Disk(s)      | |               |       |                    |    |________________|       |____________________|                ^                     ^                |                     |                 |                     |     _________________________________________________________    |                                         |    |                                                 |    |              System Attendant                   | |                                            |     |_________________________________________________________|        ^             ^        ^      ^   ^    ^     ^       |             |        |      |   |    |     |       |             |        |      |       |    |     |            ________________________________________________________        |         |            |     |         |    |    |      |        |         |            |     |         |    |    |      |        | Routing |Information | MTA |MS Search|POP3|SMTP|IMAP4 | | Engine | Store      |     |         |    |    |      | |_________|____________|_____|_________|____|____|______|

Note that all the Exchange-related resources are now directly dependent on the System Attendant. These dependencies are set when the Exchange virtual server is created. The effect of this change is that protocol resources such as SMTP can be brought online or go offline at the same time as the information store resource. This allows a faster failover of the Exchange virtual server. Exchange 2003 running on Windows 2003 allows clustered Exchange servers to store transaction logs and databases on mount point disks. This is in addition to the ability to store logs and databases spread across more than one physical disk resource. In scenarios where Exchange data is placed on more than one physical disk resource, it is imperative that the System Attendant resource be made dependent on all physical disk resources that contain Exchange data. If this dependency is not in place, the disks may go offline before the Exchange resources. This leads to data corruption or extended recovery times. For more information about Exchange 2003 cluster and mount points, click the following article number to view the article in the Microsoft Knowledge Base:

318458 Volume mount point support for an Exchange Server 2003 cluster on a Windows Server 2003-based system

Note By default, the POP3 and IMAP4 resources are not created. If you create POP3 and IMAP4 resources manually, you must manually set a dependency on the System Attendant.

When you upgrade of an Exchange 2000 Exchange virtual server to Exchange Server 2003, the resource dependencies are changed to the new Exchange Server 2003 resource dependency tree. These changes are recorded in the Exchange Server 2003 Setup Progress.log file under the ScUpgradeResourceDependencies process. The following section is an example of this section of the Exchange Server 2003 Setup Progress.log file, where the SMTP server EVS-01 Exchange virtual server is upgraded: [08:36:54] Entering ScUpgradeResourceDependencies [08:36:54] Checking dependencies of resource 'SMTP Virtual Server Instance - (EVS-01)' [08:36:54] Entering ScChangeResourceDependency [08:36:54] About to change resource dependency for resource 'SMTP Virtual Server Instance - (EVS-01)' [08:36:54] Leaving ScChangeResourceDependency

You will see entries similar to this entry for each Exchange 2000 resource that is upgraded to Exchange Server 2003.

Note To verify the resource dependencies, use the Cluster Administrator program.



For more information about Exchange Resource dependencies, click the following article number to view the article in the Microsoft Knowledge Base:

810860 Architecture of the Exchange Resource dynamic link library (Exres.dll)

Additional query words: XADM clustering EVS

Keywords: kbtshoot kbinfo KB821833

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