SAN Strategies and Case Studies, Large and Small

By Lowell Rapaport

Storage area networks (SANs) are an increasingly popular tool for storage management. SANs bring all storage devices and servers in the enterprise - either on local networks or in remote offices - under a single management umbrella on a separate network. This enables databases and other applications to access data without having to compete with user traffic for bandwidth. Also, by putting all the storage in one place, an administrator can manage it from a single console rather than logging into multiple independent storage servers. Scaling can be as easy as plugging a storage device into a network port. These advantages have led many storage vendors to add SAN features to their software.

Small-Scale SAN

Law firm Clark, Thomas & Winters of Austin, TX, developed a SAN in order to add storage and cluster the organization's many servers. The firm had fairly typical document management requirements. They rely on a GroupWise document management system plus email and accounting systems.

"We have 300 users who need 24/7 support," says Tony Armendariz, Clark, Thomas & Winters' information systems manager. "It is important to make sure we have full failover. The firm did not want to have to worry about a server going down."

The law firm installed a Magnitude storage area network system from Xiotech, Eden Prairie, MN. The simple, single-box system incorporates 216 GB of RAID storage and supports clustering of the firm's Novell servers. Armendariz didn't use virtual file system software because the firm wanted to maintain separate servers for each department.

"The SAN improved performance and reduced the number of server crashes," says Armendariz. "Our ultimate goal is to have ten servers with five of them in a single cluster."

The firm plans to replace its current SCSI DLT tape drives with fibre channel drives that will enable continuous live backups. This will ensure 24-hour access to data with backups that are never more than a few hours old.

Large-Scale SAN

Storage service providers are ASPs who specialize in storage. Their customers are organizations that need high availability storage but that either don't have the resources to deploy high-end storage or prefer to deploy their technical resources elsewhere. Either way, storage service providers find themselves supporting customers with a variety of storage needs.

StorageNetworks, Waltham, MA, is a high-end provider of outsourced storage capacity. Its customers typically have mission-critical storage demands, but they have little interest to address this challenge internally. This includes prominent dot-com customers such as Yahoo!, Lycos, Computer.com and eCircles.com. Not surprisingly, SAN figures prominently in StorageNetworks' support infrastructure.

StorageNetworks' SAN is designed for high availability and performance. It employs some of the most advanced features of fibre channel technology, such as the ability to operate over optical transmission lines for long distances. The company has more than 20 physical installations around the world, including Boston, New York, Houston, Washington D.C., Atlanta, San Francisco, Seattle, Chicago, Los Angeles, Denver, Philadelphia and London, England. Data is mirrored between local SANs in each metropolitan area. The scope of StorageNetworks' SAN gives it high reliability in case of disasters.

StorageNetworks uses a variety of equipment for its SANs including EMC RAID systems for storage, Brocade switches and Dell and Compaq servers. Other devices and software are chosen depending on whatever is most appropriate for a particular customer's requirements.

SAN Integration

SANs generally have multiple layers of hardware and software that must all work together, so most SANs are installed by specialized integrators. One such integrator is Patuxent Technology Partners of Clarksville, MD. Patuxent installs SANs for corporations and government agencies that require high bandwidth access to storage.

One challenge for every integrator dealing with SAN is combining new and existing equipment, says Hoot Thompson, Patuxent's senior technologist. "We simply put a fibre channel [interface] on the existing servers and connect them to the fibre network," Thompson says, explaining Patuxent's answer. "The software and file system on the legacy servers remain intact. A virtual file system like ADIC's Centravision or Tivoli's Sanergy makes it available to the SAN."

Patuxent's approach lets companies leverage their existing investments in optical storage and tape archives. The basic cost for a SAN starts at $75,000 to $100,000, according to Thompson. He says this cost covers a scalable framework upon which you can build an enterprise. With SAN's scalability, you need only start with enough storage for your immediate needs. Storage gets cheaper every day, so it makes sense to put off purchases until they're actually needed.