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Mike Taylor's reaction to the idea of storage service level agreements (SLAs) is typical: They haven't hit his high-priority list yet, but he suspects that will change fairly quickly. "We really don't have formalized service levels for storage at this point," says Taylor, a storage administrator at Capital Blue Cross in Harrisburg, PA. "But I do see them coming."

Storage hasn't historically rated separate SLAs--with the huge exception of disaster recovery but Sept. 11 cast disaster recovery plans into high gear, and senior executives started paying attention. Moreover, storage technology has steadily grown more complex in the past several years, causing IT departments to consider the value of creating storage-specific SLAs.

Then there's the influence of storage service providers that use SLAs as part of the contracts they sign with clients. "The use of storage SLAs really accelerated in the late '90s as SSPs started selling," says Al Sporer, the global practice manager for operations management consulting at EMC. "We've seen the concept start to move to internal IT departments in the past couple of years."

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What rates an SLA?
Gartner group analyst Raymond Paquet points out that only user-oriented storage services rate SLAs. His choices:
  • Recovery
  • Provisioning
  • Copying data for user testing
  • Production services
Other common storage measurements, such as the following, are better suited as internal IS metrics rather than an SLA:
  • Availability
  • Performance
  • Backup

Most importantly, CIOs and storage managers view storage SLAs as a tool to rein in storage spending. As the economic downturn drags on in many industries, CIOs need to cut costs. Storage--which many experts say can take up to 50% of an IT department's capital budget--has long fallen into the murky category of "necessary, but hard to track financially."

Small wonder, then, that storage expenditures have come under increased scrutiny. "Executives are beginning to ask why the bean counters can't account better for storage spending," says Dan Tanner, an analyst with the storage research group at the Aberdeen Group, Boston, MA.

SLAs aren't wholly about service--they're also about money. "If you apply cost to a policy, you've got the beginnings of an SLA," says Mark Friedman, the vice president of storage technology at DataCore Software in Ft. Lauderdale, FL.

SLA challenges
Although corporate interest is being piqued by the notion of storage SLAs, issues clog the road to smooth implementation. It's all very well to sign agreements specifying applications will be backed up nightly, or disk space allocated within 48 hours of a request, but what's the point if IS can't fulfill the requirements of the SLA? For example, Jerome Wendt, a senior storage analyst at First Data Resources in Omaha, NE, envisions storage as an in-house utility. Regardless of what SAN your server is plugged into, "you should be able to call us and get storage," he says. But he can't currently guarantee this is going to happen, so won't make promises.

For storage SLAs to have teeth, they must work properly. The first step is to find out what the main challenges are in implementing storage SLAs. And then know what to measure and what services make little sense to measure.

At many companies, "If there are SLAs in place, they are so generic that they're useless," says Steve Duplessie, founder and senior analyst at Enterprise Storage Group, a storage research company based in Milford, MA. Tanner agrees. "Companies using any sort of chargeback are using a more or less gross measure, maybe megabytes or gigabytes," he says. The end result is an SLA with no bite. He says, "If the backup SLA is, 'OK, I'll back stuff up,' what does that really mean? Users want to know that at x period of time--no matter what happens--they can restore applications within a certain level of time."

By making SLAs more granular, it's simpler to tie specific costs to each service level, which means that storage managers can give users better information about storage costs, and users can make more informed decisions. Duplessie gives a hypothetical example: "Let's say a department has 3TBs of data sitting on an IBM Shark. But in six months, that data hasn't been accessed. Does it really belong on the most expensive level of storage? The SLA should be written at a level of granularity to address this." For example, "If data isn't accessed within x months, IS can move it off the most expensive storage and put it on less expensive stuff."

At MasterCard International in New York City, for example, IT operates on a chargeback basis. By sticking with just a few storage vendors, Jerry McElhatton, the president of global technology and operations, says that lower costs lets him offer better service level agreements. "We provide a service and have service level agreements," he says. "And by having volume discount on storage purchasing we were able to eliminate multiple data numbers." That, in turn, made it easier for the group to stay within acceptable windows of service.

This was first published in February 2003

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