Taking the tears out of tiered storage

In an environment where the increase in data shipped for storage far outpaces the decreases in storage costs, tiered storage looks like a no-brainer. Making it happen is turning out to be a brainteaser even for the smartest IT shops.

All data is not created equal. Therefore, all data should not be stored the same way. It's easy enough to say. But companies are discovering that implementing a tiered storage approach is a tall order -- requiring close consultation with business units, buy-in from top management and rigorous cost-benefit analysis.

"Unless you have a strategy for dealing with the organization and with the business impact of tiered storage, it is very difficult to make it work," said Jim Damoulakis, chief technology officer at GlassHouse Technologies Inc., a storage services consultancy in Framingham, Mass. "It is a people-intensive project."

Often the additional complexity isn't worth the potential savings.
Jim Damoulakis
CTOGlassHouse Technologies

The amount of storage being shipped in raw terabytes is growing 50% to 70% annually, say experts like Damoulakis. Storage costs are coming down about 30% a year -- a positive, yes, but insufficient for sure to offset the growth in data. Indeed, the cost of storage infrastructure is the single largest capital expenditure in the IT budget in most organizations. "It's become a big enough item to become noticed," Damoulakis said.

Tiered storage -- the assignment of different categories of data to different types of storage media in order to reduce total storage cost -- offers IT shops a more business-savvy approach to data storage. IT organizations are eager to try it. Creating a tiered storage infrastructure was voted the No. 1 project for 2006 by users at a recent Storage Decisions show in Las Vegas. Storage vendors are happy to sell you multiple tiers of storage. But according to GlassHouse, 80% of large companies -- organizations with petabytes of data, hundreds of thousands of applications and plenty of reasons to cut storage costs -- still keep data on a single tier. How come?

Part of the challenge is that while IT shops have responsibility for and visibility into the cost side of storing data, they have little or no control over assigning a value to that data. Moving data from one tier of storage to another requires a business justification. "The effort to get agreement from whoever owns the data to move it to a lower tier is a huge challenge. Every business unit thinks the data they deal with is the most important in the company," Damoulakis said. "Then the effort of actual migration and potential disruption to the business of migration is a problem."

When GlassHouse goes into a company on a tiered storage assignment, for example, its consultants show up armed with questionnaires aimed at assigning values to the data and identifying potential storage savings. Business users are grilled about the application -- its performance level, the impact and ramification of an outage, etc. The IT shop is queried about its data management policies and costs. Companies usually do a pilot first to build a business case for tiered storage, focusing on one to five applications (albeit large ones, like SAP or PeopleSoft). That can take four to eight weeks to complete. "Companies that are doing tiered storage are taking a crawl, walk, run approach," Damoulakis said.

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For companies that can't afford the outside consultants, his advice is to go after the easy pickings first: disk-based backup and e-mail archiving are good candidates for lower-tiered storage. Test data should not be stored on the same tier as the actual production data.

Small companies must also be mindful of the costs of managing multiple kinds of storage systems. "Often the additional complexity isn't worth the potential savings," he said.

Analyst Adam Couture, who covers storage at Stamford, Conn.-based Gartner Inc., said the technical challenges of tiered storage should not be underestimated. "How do you port data from one tier to another? How do you move data as its business value changes over time, or as its classification changes over time? After that, how do you make sure that the people who need the data still have access to it? " Couture said. "These are the sorts of things that can be a real pain in the neck."

He agreed that getting business units to rank their data is also tough. "Under the 'all data is created equal' mentality, you put everything on Tier 1 storage, EMC Symmetrix DMX or Hitachi TagmaStore. You fully replicate it synchronously to a second site and have yet a third hot site for disaster recovery. Very expensive!" Couture said. "Not every piece of data in the same company needs to be protected and replicated like that."

It helps if business units know the pricing for various tiers of storage. That is not always easy to do at companies where storage is handled as a corporate tax. At companies where storage costs are charged back to the business units, providing price points in the chargebacks for the tier of storage the data sits on sends a "very powerful message all by itself," Couture said. "If I am a business unit and can see that I really don't need this class of storage for my application, then maybe I have more money to invest in marketing or a new hire."

Another way IT can help make the case for tiered storage is to speak in business terms, Couture said. Business users should also not have to care about seek times, response and how many rpms the disk is spinning on. He knows a clinic that set up service-level agreements based on the time the patient checks in to the time the patient gets to the doctor's office. "That's how much time IT has to get that patient's radiological records. The clinic needs the X-rays sitting in the doctor's office when the doctor gets there. Then it's up to IT to worry about the cheapest and best way to do it."

Let us know what you think about the story; e-mail: Linda Tucci, Senior News Writer

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