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SAN Expansion Best Practi:

How to select a storage capacity planning tool

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Managing storage as it proliferates in an enterprise is a big challenge. The key to storage management is capacity planning -- understanding how much storage is available, knowing where the storage is located and allocating storage resources to users and applications.

Today's storage managers must see beyond the bytes to understand the nature, attributes and value of the data itself. Once administrators understand the data, know who owns it and see how the data is being used, they can make smart capacity planning decisions about enterprise storage and data protection.

All the hype surrounding storage management products can complicate the process of choosing a storage management product. Having the ability to manage multiple storage systems through a single product is a key criteria. But after that, you'll need to plod through an overwhelming array of features and capabilities to identify the best tools for your situation. This section of our guide to SAN expansion explains how to identify the best storage management and capacity planning tools.

Best Practice No. 1: Understand storage utilization and other key attributes

The first benchmark for a storage management and capacity planning tool is to identify the available storage and report how much of your total storage capacity is actually being used. Any storage management tool should be able to provide this type of information, but it must interoperate with your storage platforms. Storage area network (SAN) storage typically runs at 60% to 85% utilization. If your SAN consistently runs at less then 60% utilization, you have excess storage capacity that you could have purchased later, in all probability at a lower cost . If storage utilization is more than 85%, you should probably add more storage soon to avoid application performance problems.

A good capacity planning tool will monitor storage utilization over time and offer users storage purchase recommendations. Ideally, the amount and timing of any storage upgrade recommendations will prevent any application performance problems, while avoiding wasteful overbuying. Capacity planning tools typically get more accurate over time as near-term and long-term trends can be tracked.

Once you have a handle on storage utilization, examine all the available storage characteristics, such as response time, latency, IOPS, throughput, bandwidth and power demands. "A balanced plan should address performance, availability, capacity and energy consumption (PACE)," says Greg Schulz, founder and senior analyst at the Storage IO Group.

Best Practice No. 2: Translate growth rates into costs

Managing storage growth is the best way to manage storage costs, so it's important to understand how your compound annual storage growth rate relates to your storage budget. "The magic number is 55%," says Phil Goodwin, president of Diogenes Analytical Laboratories Inc. "If your compound annual growth rate is 55%, then you have a neutral purchasing budget." That is, even though new storage capacity is still expanding, storage prices typically decline roughly 35% to 40% each year.

Best Practice No. 3: Include data classification and migration features

Many older storage management tools stop at utilization and capacity analysis -- omissions being corrected in newer products. "It's dubbed 'SRM 2.0,' " says Stephen Foskett, director of data practice at Contoural Inc., citing a proliferation of coming products that examine file ownership, application relationships and other requirements.

Once data is identified and classified, it is possible to match storage resources with particular data types. Mission-critical data types can reside on expensive high-performance storage, while nonessential data types are placed on less expensive commodity (near-line) storage. This is the premise behind tiered storage, and it can have a profound impact on storage costs. Consider tools with replication or migration features. Once a piece of data is identified, such tools can automatically move that data to its appropriate storage tier.

Best Practice No. 4: Replace older tools with heterogeneous tools

Take every opportunity to reduce the number of storage management tools in the enterprise. "A lot of companies are adding storage [management functionality] to their enterprise management tools," Foskett says. Having fewer tools will simplify the learning curve for storage administrators, reduce licensing expenditures and ease software maintenance tasks. However, storage administrators must select a management tool that supports all (or most) of the storage systems currently deployed. It's acceptable to use more than one management tool where needed, but don't ignore the goal of simplification.

Best Practice No. 5: Use data deduplication to maximize storage efficiency

Data deduplication has attracted much attention for its ability to eliminate redundant content. Although deduplication is not yet a native feature of most storage management tools, this "intelligent compression" has become a vital part of archival or content addressed storage (CAS) platforms. Data deduplication can provide levels of compression up to 50 to 1.

Best Practice No. 6: Factor data retention into storage growth and management

Data must also be kept for some prescribed period of time, which varies by business and industry. Storage administrators must account for retention in any capacity planning or management activity, and capacity planning tools should in turn account for that type of storage growth due to data retention. Similarly, storage management tools should support and enforce retention policies wherever possible. When data retention periods expire, the management tool should also implement secure deletion to ensure that unneeded data is eradicated as soon as possible.

Best Practice No. 7: Ensure adequate scalability for near and long-term storage growth

Management tools must scale to accommodate hundreds of devices, support dozens of operating system versions and operate across LAN, WAN and SAN connections. Storage administrators must understand and test the limits of scalability and decide when infrastructure growth should justify a new software version or an entirely different management product.

Best Practice No. 8: Storage management should include virtualization

Server virtualization allows one physical server to host numerous logical (virtual) machines; storage virtualization allows various physical storage devices or systems to be treated as a single ubiquitous storage resource. Both approaches improve utilization and forestall new purchases. Storage management tools should always include support for virtualization and popular virtualization platforms. "Consider [management] tools that natively support VMware," Foskett says. "They can tell you the allocation of your storage LUNs, the virtual LUNs that VMware instances are seeing, the virtual disks that they're using and what's on them."

26 Oct 2007