Evaluate issues of compatibility and interoperability. A capacity planning tool must be able to see or autodiscover storage systems and track the complete storage picture across an enterprise. Otherwise, the tool is useless. One of the first purchase considerations should be to ensure interoperability with existing storage systems. If new storage purchases are already planned, ensure that the tool will also work with pending purchases. Also, take the time to gauge a capacity planning tool against your own internal processes. It should provide the necessary information at a level of granularity that is most conducive to your particular budgeting/purchasing process.
Determine the role of software agents. Most capacity planning tools require the use of agents. For example, StorageConsole software from Aptare deploys an agent on the master server, while NetWisdom from Finistar touts agentless operation. Since agent software requires more maintenance and attention, storage administrators may prohibit the use of agents. If your organization's IT department prohibits the deployment of server agents, focus on "agentless" capacity planning tools and verify that your planning tool can collect the required suite of data across your storage platforms without agents. However, remember that reporting may not be as detailed or comprehensive as the reporting from capacity planning tools that rely on agents.
Consider the analytical capabilities of the tool. Understand exactly how the capacity planning tool analyzes information. For example, some specialized tools may simply examine the storage capacity available on network servers or measure network bandwidth. More versatile tools may actually be able to model the needs of a particular application, such as the resource capacity required for a new distributed application. Some capacity planning tools can also predict the performance and availability of applications relative to storage.
Consider the reporting capabilities of the tool. Once the capacity planning tool completes its analysis, it needs to generate a report that provides pertinent details. For example, some tools can report on storage space usage and storage performance, such as I/Os, throughput, response/latency, I/O size, reads and writes. Other tools might provide application-centric, server-centric, storage-centric, or network-centric views of the environment. Every organization is different, so look for the reporting details that you actually need.
Test the tool for predictive accuracy. If you expect the capacity planning tool to help with modeling or predictive analysis -- even "what if" scenarios -- make it a point to test the tool in a lab setting that mimics your real environment. Not only will testing help to identify the most accurate tool, it will also afford an opportunity to evaluate the user interface and steps needed to conduct a model. Inaccurate or difficult modeling will really impair your use of the software. Another way to verify a tool's accuracy is to speak with other users.
Consider capacity planning features in an SRM suite. Although dedicated capacity planning tools remain popular, there is a growing trend to bundle capacity planning features in a broader storage resource management (SRM) product or suite of tools. Purchasing a suite can sometimes save money (over buying elements of a suite separately) and avoid potential software integration problems because the components of a suite are already known to work together. Some organizations purchase a capacity planning tool when a short-term tactical problem needs to be solved, or opt for an SRM or other software suite when longer term strategic planning/reporting goals need to be addressed. (See the previous chapter on SRM tools).
The capacity planning tool specifications page in this chapter covers the following products: