One of the more difficult tasks when planning for a migration to a virtual datacenter is calculating the resources necessary to produce a stable and scalable result. PlateSpin’s PowerRecon is a good example of a software tool to help determine these numbers. PowerRecon runs on a dedicated server and hooks into existing servers in the datacenter via WMI and SSH, generating performance data over time and using that information to gauge the virtualization host server requirements. It can tell you how many virtual server hosts will be needed to successfully reproduce the physical environment in the virtual realm.

Strangely hidden among VMware’s offerings is the company's framework for providing the same functions. VMware Capacity Planner is a combination of a local app and a hosted service. A Windows-based application runs within your datacenter, gathering performance data from all your servers in much the same way as PowerRecon, but that data is then shipped to VMware’s servers for processing.

VMware Capacity Planner is rife with reporting tools that provide far more information than you need just to plan your virtualization strategy. Nicely appointed reports show the current datacenter workload, split by OS, server architecture, application, and more, and the consolidation scenarios give a great overview of how the existing infrastructure could look as a virtual infrastructure, down to the new hardware (makes, models, and specs) to be used for the VI3 hosts, which existing physical servers could be repurposed for work as VI3 hosts, and where existing server personalities should be placed in the virtual world. In fact, even removing the virtualization planning components, the reports are so useful that Capacity Planner could easily double as an analysis-and-reporting tool for whole, non-virtual infrastructures.

Capacity Planner allows you to create templates for consolidation scenarios that balance needs against a given supply of physical resources. For instance, you could create a template that dictates specific hardware -- Dell PowerEdge 2950 servers with 8GB of RAM, two dual-core 3.0Ghz CPUs, and four gigabit NICs, for example -- to be used as VI3 hosts, and set flags to enable the re-use of existing hardware in the final plan. The resulting scenario might then dictate that multiple different applications and guest OS types be run on the same VI3 servers, and that the servers currently spread across multiple locations be consolidated into one datacenter. Once all these parameters are gathered, you can run reports that show the number of new servers required, the existing servers to be re-purposed, and essentially, how the datacenter will look following a migration to VI3.

By providing Capacity Planner as a hosted service, VMware can collect data on application performance and requirements from every infrastructure that it analyzes, resulting in better decisions on app placement within each virtual infrastructure. VMware can also make changes to the tool quickly and frequently without requiring new software to be installed by customers. Why VMware hasn't banged the marketing drum for this tool is anybody's guess, but the beta version that I looked at definitely seemed ready for prime time, and perhaps it will enjoy a higher profile following the official release of the new version.