Consolidating servers with virtualization seems basic enough, but many enterprise-class organizations have difficulties deciding where to host their virtual machines (VMs).
To help with this process, Microsoft offers a free Hyper-V server consolidation planning tool -- the Assessment and Planning Toolkit -- for Hyper-V hosts. This server consolidation tool produces a report that outlines your VM-to-host ratio, resource utilization and network throughput after consolidation.
When you create a server consolidation plan, ensure that a host has sufficient resources to accommodate multiple VMs. You should also allocate VMs among hosts in a way that makes sense. You don't want, for example, to put all your virtualized domain controllers onto a single host server. If that host fails, you're left with no functional domain controllers. Microsoft's Hyper-V server consolidation tool automates this decision-making process.
Server consolidation planning and assessment
The first step in server consolidation planning is to compile an inventory of the servers running in your infrastructure. The Assessment and Planning Toolkit contains a wizard to help you take inventory.
When you first launch the Inventory and Assessment Wizard, select the types of servers that you want to inventory (see Figure 1).
Next, you'll be taken to a screen that asks which methods you want to use to locate the computers on the system. By default, the wizard uses Active Directory and various Windows networking protocols, but you can select other methods, such as scanning an IP address range.
From this point forward, the options vary depending on the discovery methods that you have chosen. After you answer the various prompts, the wizard compiles an inventory (see Figure 2). Depending on the size of your network and your chosen discovery methods, the inventory collection process can take time to complete.
When the process is complete, the console tree displays the computer inventory results. Figure 3 shows that the machines are arranged in groups of physical and virtual machines. In this screen, any machine that was powered down during inventory will show a failed-connection status.
Server consolidation planning decisions
The next step is to compile a list of servers that you want to include in your server consolidation plan. Oddly enough, you cannot use the inventory tool for this purpose. Instead, you have to create a text file with the various Hyper-V server names. Still, the inventory list helps you determine which servers to include in the text file.
After you create the text file, you have to gather some performance metrics on the servers that you've chosen to consolidate. To do so, navigate through the console tree to Server Consolidation > Performance Metrics Results. Then click to launch the Performance Metrics Wizard. This wizard requires you to enter the name of the text file and to answer a few simple prompts. It then compiles performance data for the servers listed in the file. This process takes about an hour.
The server consolidation tool's report
When the server consolidation planning tool finishes compiling performance data, it's time to work on the consolidation report. Navigate through the console tree to Server Consolidation > Server Consolidation Results. Then click on the Server Virtualization and Consolidation Wizard link.
The wizard prompts you to specify the virtualization technology that you use. As you would expect, this server consolidation tool supports only Microsoft virtualization products.
Next, the wizard asks about your host's hardware configuration. You can choose from your hardware library or use your current hardware configuration. The first time that you run the wizard, you have to choose the Current Hardware Configuration option. Then it asks several questions about the host server's hardware configuration.
After you enter the configuration, you are taken to the Host and Guest Threshold screen (see Figure 4). This screen allows you to limit the number of VMs running on a host. It also allows you to reserve additional physical memory and disk space -- beyond what is required -- for each guest machine.
Finally, import the text file containing the list of servers that you want to virtualize. The wizard then displays a summary of the configuration information that you have provided. Check the summary to ensure that it's correct, and click Finish.
The wizard compiles a server consolidation report that includes resource utilization before and after consolidation. The report also indicates which servers are virtualization candidates, the average number of VMs per server, and how much memory, CPU and disk I/O the servers will use (see Figure 5).
Server consolidation planning and implementation can be a messy process. It's possible to allocate guest machines to host servers manually, but that leaves room for error. The Microsoft Assessment and Planning Toolkit can help you eliminate such errors by automating server consolidation planning.
Brien M. Posey, MCSE, has received Microsoft's Most Valuable Professional Award seven times for his work with Windows Server, IIS and Exchange Server. He has served as the CIO for a nationwide chain of hospitals and healthcare facilities and was a network administrator for Fort Knox. You can visit his personal website at www.brienposey.com.