Switches rethink virtualization challenge

Virtualization of storage data across multiple-vendor arrays has long been a dream of vendors and enterprises. A few are getting it right.

A new crop of vendors, including Brocade Communications Systems, Cisco Systems, and Maranti Networks, are rising to the virtualization challenge by bringing more intelligence out to the network edge.

Several switching platforms are due for summer release. The companies aim to deliver storage applications to multiple storage arrays manufactured by different OEMs.

Each switch is designed to host applications and make decisions after inspecting and processing packets with customized ASICs at each port.

San Jose, Calif.-based Brocade has been most vocal about its plan of attack. Thanks to its acquisition of Rhapsody Networks, Brocade is prepping a family of switches called the Brocade Silkworm Fabric Application Platform. According to Jay Kidd, vice president of product management, the platform will move storage management functions such as volume management, backup and recovery, and performance management into the fabric and out of the array and the hosts.

The Brocade architecture is similar to its competitors in that a switch is designed to reside between the servers and storage arrays. As a result, it can provide one place for applying network management policies, eliminating the need to regularly update software on multiple servers.

According to unnamed sources, Cisco's switch platform is a blade that fits into the San Jose, Calif.-based company's MDS 9000 family, which was introduced in August 2000.

Like Brocade, Cisco is working with independent software vendors to migrate their current host-based applications to the Cisco MDS 9000.

Also developing a switch platform is San Jose, Calif.-based startup Maranti Networks. Rick Walsworth, director of product marketing said his company's approach is different from that of Cisco and Brocade. Maranti Networks is approaching the issue in the same way networking companies did in the late 90s.

"We're making decisions in the data path," said Walsworth of Maranti's forthcoming switch. "Our competitors are taking the packet out of the data path and into a blade to make a decision, then back to the disk."

Walsworth said this approach affects latency and throughput -- two things he said enterprises won't compromise. "The issue is, if you add latency the applications will suffer," he said. "We're doing the packet processing at the port."

Maranti, unlike Cisco and Brocade, is working on building its own applications to reside on the switch.

While the platforms are generating buzz, some critics are saying that performance and scalability issues haven't been addressed. Some analysts and independent software vendors argue that the switch alone is not the only solution. Virtualization software will be found in all three pieces of the SAN and not just in the new switches.

"As we move forward, functionality will reside in different areas dependent on the function," says Nancy Marrone, senior analyst at Enterprise Storage Group. "Some make a lot of sense on a switch." She listed replication, mirroring, and snapshot capability as obvious candidates.

For that to happen, Cisco and Brocade need third-party ISVs to port their software to the new platform -- an endeavor that is turning out to be more difficult than either managed.

To date, no ISV has announced its software can run on either platform, although both say ISVs have signed up to port their software.

And in another potential sign of trouble, unnamed sources report host-based storage software specialist Veritas is having a difficult time writing its software to the new switches.

Meanwhile, Brocade and Cisco must convince array vendors such as EMC, Hewlett-Packard, and Hitachi Data Systems to port their array-based software to the forthcoming switches.

Ken Steinhardt, director of technology analysis for EMC, says a switch is not the right place for local replication software, but says it might be right for remote replication. In other words, EMC has no immediate plans to port its replication software over to the switches.

HP intends to port its VersaStor to the Brocade platform, but hasn't revealed when that would occur.

On the ISV front, the storage switch is getting a better reception. Greg Tevis, product manager for IBM Tivoli's SAN Manager, reports that the company is interested in the concept.

"Adding software to switches certainly has some merit," Tevis said. "We're currently having conversations with several fabric vendors."

Tevis said there are concerns and trade-offs with the architecture, citing the impact of performance to the switch.

Previous attempts saw virtualization software running in dedicated SAN appliances, Tevis added. These devices have not typically been well received by enterprises due to the fact that they slowed performance and did not scale as the number of applications grew.

Augie Gonzalez, director of product marketing at Datacore, a virtualization software start-up, shares these concerns. Gonzalez said Datacore, which is based in Fort Lauderdale, Fla. , is working with these switch vendors to port their software to the platforms.

"It makes sense and they've asked us to participate," Gonzalez said. "It's another way to license our software and reach our customer base."

Gonzalez questioned how well a switch can host applications, arguing these switches must be optimized for speed. He also admitted ISVs are accustomed to general processors found in servers rather than custom ASICs. "ASICs don't provide rich development environments," he said.

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