Let’s talk about Exchange 2000 Server clustering. I'm configuring a 4-node Windows 2000 Datacenter (Win2K Datacenter) cluster running Exchange 2000. I want to share some of my frustrations, challenges, and lessons learned thus far.
On one hand are the frustrations of Win2K. Windows 2000 Advanced Server (Win2K AS) supports 2-node clusters and seems to work fine (it should—it's released software, right?). Datacenter, on the other hand, is not a released product, and I had problems getting four nodes to join the cluster. The most troublesome problem was getting the cluster to manage shared disk resources. Managing shared disk resources is important because an Exchange 2000 cluster must be able to access shared storage in the cluster to define virtual servers and storage groups. To be fair, the shared disk concerns were mainly Win2K problems and not directly related to Exchange 2000.
The main problem with Exchange 2000 is that 4-node support is not technically ready or supported by Exchange development in Release Candidate 1 (RC1). Therefore, I can’t hold anyone responsible for my difficulties (or call technical support). My concerns revolved around keeping track of six Exchange Virtual Servers (EVS) running on four nodes. Nodes 1 through 3 had one EVS, and node 4 had three. EVSs running on nodes 1 through 3 would fail over to any of the nodes (1 through 4), and the three EVSs running on node 4 would fail over to nodes 1, 2, and 3, respectively. The complexity of defining an EVS is also a problem. In Exchange 2000, you create an EVS after you've defined the IP Address, Network Name, and Physical Disk resources, and brought them online. Next, you must create an Exchange System Attendant Resource, which configures the remaining Exchange 2000 Virtual Servers and resources. As you can see, this process is complicated. Clusters with two nodes are simpler; with four nodes, things start to get out of control.
What lessons did I learn? First, before you try to cluster anything for Win2K, make sure that your hardware devices have the latest ROMs and Win2K drivers available. Most vendors have Win2K firmware updates available, and the Win2K release to manufacturing (RTM) version doesn’t usually contain the latest device drivers. Next, understand how your system manages and configures shared storage in a cluster environment. I can’t tell you how confusing it was to try to keep track of four system disks, a quorum disk, and logical drives defined for each virtual server instance in the cluster. Finally, I should have spent more time understanding how Exchange 2000 creates, manages, and uses virtual servers. I made many mistakes because I didn't understand how Exchange 2000 clustering works.
Overall, working with Exchange 2000 clustering was a great exercise, despite my frustrations. I hope that learning about my experiences helps you avoid the same mistakes when you begin experimenting with Exchange 2000 clusters. When we figure it out, I think Exchange 2000 clustering will be a welcome addition to our Exchange reliability portfolio.
