SANs - the next networks?

SANs - the next networks?

With the capacity of some data-bases expected to increase to 800 petabytes (800 quadrillion bytes) in the next two years, Storage Area Networks (SANs) are emerging as one way organisations can give users fast access to data without taxing the LAN.

Uncoupling storage systems from host server bus connections, and consolidating storage in high-speed networks at the server "back end", are the key elements of SANs (also known as System Area Networks), according to supporters of the concept.

"We need to externalise storage out of the server. We gain great benefits this way: central-isation, easier attachments and scalability, better availability, and efficiency," said Michael Peterson, president of Strategic Research, in the US.

Separating and consolidating network data storage and its concomitant functions onto a SAN not only eases storage management, but also enhances the performance of mission-critical LAN traffic, according to Peterson and other analysts.

"When you implement a SAN, you can leverage the strength of each [network] system," said Tom Lahive, a senior analyst at Dataquest's enterprise storage group.

Given that the concept is evolving, users of full-blown SANs are still uncommon. But the architecture does have its pioneers.

Managing data requirements and maintaining availability are now the principal concerns of IT managers, Peterson said.

Creating a shared resource of external, consolidated storage once removed from the servers is becoming increasingly common to accomplish these aims, he and other computer professionals agree.

"The trend is definitely toward making storage an independent function within the network," said Gil Press, manager of network storage marketing for EMC.

"Storage was almost an afterthought [in years past]," Press said. "[Now] servers themselves are almost becoming the peripheral."

An important feature of SANs is they typically link to host servers via hardware using Fibre Channel communications protocols and topologies.

Protocol independence

Fibre Channel connections and devices, which are significantly faster than their SCSI counterparts are the lifeblood of SANs, analysts and manufacturers said.

Fibre Channel also has the advantage of virtual OS and protocol independence, allowing wide latitude in its implementation.

Another characteristic of network alterations is the move toward clustering servers together for higher availability and scalability, where products such as Microsoft's Cluster Server are expected to have an impact.

SANs will accompany these developments, analysts said.

Sun's own cluster initiative, Enterprise Cluster, forecasts the use of SAN, or SAN-like, storage.

"Our vision of storage is that of a network," said Andy Ingram, director of enterprise server marketing for Sun. "To get many hosts communicating to many devices, and getting more intelligence out of the storage fabric," Ingram added.

Even SAN supporters admit, however, that it is not so much a radically new as a new-found idea.

"For all intents and purposes, the basic SAN technology has existed since the first mainframe," Lahive said.

"We're not inventing something new, we're only describing concepts," Peterson acknowledged.

Other industry observers are highly sceptical of SANs, primarily due to a perceived dearth of controlling software.

"Different hosts manage storage differently. The trick is the software to manage the storage," said Paul Vellanti, a research analyst at International Data Corporation (IDC), in Massachusetts.

Without coherent software to manage interconnected LAN-SAN systems, "you are in effect negating the SAN advantage," Vellanti added.

"[SAN] is a new buzzword," said Paul Mason, a research analyst at IDC. Until the systems get intelligent enough to decide where to store [and retrieve] data for you, [SANs are] a first crude step."

Yet supporters insist that SANs offer a unique solution to a common problem - fast access to large amounts of data - that will not go away any time soon.

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