A VMware Clustering Recipe

Microsoft's enterprise-class clustering solutions have evolved like a fine wine, getting better with age. Unfortunately, like such wine, the cost of implementing and testing Microsoft clustering solutions is out of reach for many. I've worked with several organizations that have Microsoft Exchange Server and Microsoft SQL Server clusters in production but don't have the funds to maintain test server clusters in their labs.

To teach clustering in classrooms, I've had to purchase a dozen SCSI host bus adapters (HBAs), cables, and external SCSI drives. Even then, I was limited in what I could show the students because each practice cluster contained only one shared drive. In my travels, I've spoken with many people who wish that clustering were more portable. Administrators and systems engineers would like to be able to practice server cluster configurations outside of production. Microsoft partners and resellers would like to be able to demonstrate on their laptops a clustering solution for clients. I have the answer.

VMware—A Cluster Geek's Best Friend
I discovered VMware a couple of years ago, and I immediately liked the product. Within a month, I had Novell NetWare, Linux, and Microsoft virtual machines (VMs) running on a virtual network on my laptop, and my classroom demonstrations reached a new level. In addition to letting VMs share a network on the same system, VMware lets you configure shareable resources. (This article assumes that you have a fundamental understanding of VMware concepts. If you don't, you can find documentation at http://www.vmware.com/support/ws3/doc.)

The fact that VMware lets you share virtual hard disks between two virtual computers filled my imagination with countless virtual-clustering possibilities. I soon had a documented method to build virtual clusters on one laptop (or desktop) system. Here are the basic ingredients of my VMware clustering recipe:

• one laptop or desktop PC with 512MB of RAM and 6GB of free disk space
• one VMware Workstation 3.0 (or later) license
• two Windows 2000 Advanced Server VMs on a virtual TCP/IP network, each configured to use 128MB of RAM
• one or more shared nonpersistent virtual SCSI disks (for cluster storage)
• one 2GB IDE local virtual disk per VM (for OS data)
• one or more virtual network cards on each VM (for cluster communication)

Building the Virtual Cluster
As with any good recipe, the ingredients alone aren't enough. When building a virtual cluster, the order of preparation is key. To begin, you need two instances of Win2K AS running as VMs on your system. For this article, I built a virtual cluster on a Dell Inspiron 8100 with a 1GHz processor and 512MB of RAM and with Windows XP Professional Edition as the host OS. I used VMware Workstation 3.2 to create the VMs. With this horsepower, I've successfully demonstrated the installation and configuration of both Exchange 2000 and SQL Server 2000 server clusters.

To build the two Win2K AS VMs, create a VM (VM1) and install and configure it as a standalone server running Win2K AS. When the installation has finished, power down VM1, then copy the contents of VM1's folder on the host system to a second folder, named VM2 (or any name you choose). Open VM2 in the VMware console. Open Configuration Editor for VM2, go to the Options tab, and give the VM a unique name. Then go to the Hardware tab and change the path for VM2's virtual disk file to point to the virtual disk file in the VM2 folder. After you configure VM2, boot it up and change its host name and IP address so that they're different from those of VM1 (I usually use names such as Node1 and Node2). This shortcut gives you a second functioning server in significantly less time than reinstalling Win2K AS from scratch on a second VM.

Now that you have two VMs, take the following steps to prepare the two servers to be part of a cluster:

1. Run dcpromo.exe to promote VM1 to be a domain controller (DC) and forest root. Use whatever domain name you want.
2. After the Active Directory Installation Wizard finishes and VM1 reboots, join VM2 to the domain. At this point, both VMs should be powered up.
3. On the DC (VM1), open the Microsoft Management Console (MMC) Active Directory Users and Computers snap-in and create a cluster domain user account. I typically call the account Cluster. Set the account so that the user can't change the password and the password never expires, then add the account to the Domain Admins user group.
4. Shut down and power off both VMs.

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