This article describes how to install an Exchange 2000 Service Pack on an Active/Active or Active/Passive cluster server with as little downtime as possible, a process known as a rolling upgrade.

A rolling upgrade is a process of upgrading cluster nodes, one node at a time, so that services and resources offered by the cluster are always available even though the nodes being upgraded are not available. This process reduces the system downtime associated with the upgrade to a few minutes, which is the time necessary to move resources from one node to another, opposed to upgrading a stand-alone server or all nodes of a cluster simultaneously. A rolling upgrade for Exchange 2000 works by using an Active/Passive or an Active/Active scenario.

To perform an Exchange 2000 rolling upgrade for an Active/Passive cluster:

1.	To update the Passive node to the latest service pack for Exchange 2000 Server, run the Update.exe program from the \Setup\i386 folder on the Exchange 2000 service pack CD-ROM. You must log on to the Passive node of the cluster by using the Cluster Service account, the same account that you used to install the Cluster Services. If you do not use this account, you may receive the following error message: An unknown error has occurred. Facility: Win32 ID no: c0075000 Microsoft Exchange Cluster Administrator Extension.
2.	In the Component Selection dialog box, ensure that Update is displayed for the nodes in the Action column next to Microsoft Exchange Messaging and Collaboration and Microsoft Exchange System Management Tools. If Update is not displayed, click Update for the Action, and then wait for the update to complete.
3.	Restart the upgraded node. NOTE: If you do not restart the node after you apply the service pack, the virtual server(s) may not fail-back correctly.
4.	Failover one or more of the Virtual Computers from the Active node to the updated Passive node.
5.	Update the node that is now Passive, to the latest service pack by running the Update.exe program from the \Setup\i386 folder.
6.	In the Component Selection dialog box, ensure that Update is displayed for the nodes in the Action column next to Microsoft Exchange Messaging and Collaboration and Microsoft Exchange System Management Tools. If Update is not displayed, click Update for the Action, and the wait for the update to complete.
7.	Restart the upgraded node. NOTE: If you do not restart the node after applying the service pack, the virtual server(s) may not fail-back correctly.
8.	Optionally, failover one or more of the Virtual Computers to the original preferred server. NOTE: To minimize user down-time, it is not necessary to perform this step.

If you are running a two-node Active/Active cluster, you can follow a similar process to update your servers to the latest service pack for Exchange 2000 Server. Before you start this process, failover your Virtual Computer so that both computers are running on the same server.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

A white paper that discusses rolling upgrades with Windows 2000 clustering is available. To view the "Windows 2000 Clustering: Performing a Rolling Upgrade" white paper, visit the following Microsoft Web site: