Clustering Challenges Storage Stronghold

Spread of stand-alone systems prompts efforts to improve NAS management

Clustered storage technology has emerged as a means for meeting a growing corporate need to better manage an ever-growing supply of network-attached storage (NAS) devices.

The technology allows IT to consolidate the management and increase the scalability of NAS, so much so that observers expect that it will one day replace the individual NAS box.

Sonja Erickson, vice president of technical operations at Kodak Easy Share Gallery, a service of Kodak Imaging Network Inc. in Emeryville, Calif., said NAS clustering technology has already saved her company hundreds of thousands of dollars in personnel costs alone.

"In terms of staffing, since we installed [a NAS cluster from Isilon Systems Inc.] a year and a half ago, we've hired no additional staff," she said. "That's hundreds of thousands of dollars saved. In terms of efficiency, it takes only a day to get the systems up and running."

The Kodak unit uses clustering technology from both Isilon and Beaverton, Ore.-based PolyServe Inc. to connect hundreds of Wintel servers at Kodak that host its online digital photo image service. Erickson uses a staff of five to manage more than a petabyte of data on the servers.

Prior to installing NAS clusters, Erickson used direct-attached SCSI arrays that lacked scalability and could take up to a month and a half to get online. In contrast, the PolyServe boxes take about a week to get online, she said, and Isilon's take about a day.

To date, most of the major storage vendors—Hewlett-Packard Co., EMC Corp., Hitachi Data Systems Corp. and Network Appliance Inc.—have released technology that can virtualize NAS systems by pooling disk capacity behind NAS engines. All have said that they are either developing or evaluating third-party clustering technology as well.

Meanwhile, start-ups Isilon, PolyServe and Panasas Inc. in Fremont, Calif., are already offering clustering software that runs across Windows and Linux.

Pushan Rinnen, an analyst at Gartner Inc. in Stamford, Conn., suggests that the clustering technology will ease management headaches better than the older virtualization technology.

Philip Rosedale, founder and chief technology officer of Linden Research Inc., a maker of online entertainment systems in San Francisco, said he has attained "extremely high I/O throughput" with a NAS cluster from Isilon that he installed about six months ago.

"We would have spent a lot more money and would have taken a lot more time with a traditional array," he said.

COMPARING TECHNOLOGIES
Clustered Storage Traditional NAS
PROS

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Cobbles inexpensive commodity servers together

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CPU workload is shared among boxes for near-linear scalability

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Automatic load balancing

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Reliable

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Simple to install and manage

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Scales well

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Reliable

CONS

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Still a niche technology

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Typically limited to high-performance Linux server farms

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Requires separate management of each box

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If one NAS head fails, performance can be affected on the second

Copyright © 2005 IDG Communications, Inc.

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