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The idea of capacity carries important implications for the storage organization. Capacity costs money, and new disk acquisitions stand out as a notable part of every IT budget. The trick is to match new capacity with actual storage needs -- buying excess storage capacity wastes money, while buying too little storage capacity can eventually result in performance problems or stalled storage projects. Gauging storage needs over time is one of the biggest challenges faced by IT administrators, and a new generation of capacity planning tools is emerging to help forecast growth and utilization of storage resources. This challenge is complicated by the diverse storage needs of applications and users -- no two storage environments are the same.

Capacity Planning Information
Visit the SAN All-In-One Research Guide for background information on SAN management, connectivity and switches.
Consequently, the selection of a capacity planning tool must include a thorough consideration of your applications. It is also important to ensure that the tool is interoperable across all of your storage systems, while still meeting all of your analytical and reporting requirements. Now that you've reviewed the essential issues involved in any SAN upgrade, this chapter covers the specific considerations for dedicated capacity planning software. You'll find a series of specifications to help make on-the-spot product comparisons between vendors, including Aptare Inc., Finistar Corp., Tek-Tools Inc. and others.

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:

  • Aptare Inc.; StorageConsole software
  • EMC Corp.; StorageScope software
  • Finisar Corp.; NetWisdom software
  • IBM; Tivoli TotalStorage Productivity Center for Data
  • Microsoft; System Center Capacity Planner 2006
  • MonoSphere Inc.; Storage Horizon 3.0 software
  • TeamQuest Corp.; TeamQuest Model software
  • Tek-Tools Inc.; StorageProfiler software

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  • This was last published in April 2007
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