What's After Fibre Channel?

James Nardi oversees hundreds of terabytes of data. Sometimes, the disks that it all resides on get hammered more than 10,000 times a second. Sometimes, they get requests only once in a blue moon.

"We can't use just one disk technology and satisfy all our storage needs," says Nardi, director of Web hosting special operations at Edgewood, Colo.-based Verio Inc., one of the world's largest Internet hosting providers.

So Verio has a significant investment in Fibre Channel technology, which delivers excellent results for demanding storage needs. But the company, like so many others, is constantly looking beyond Fibre Channel for future storage solutions. Some of the leading contenders to displace Fibre Channel are iSCSI, Fibre Channel over IP (FCIP), Internet Fibre Channel and, in the near future, InfiniBand.

Verio is looking at all of them. It has full-time technology evaluators in Virginia and Colorado who are dedicated to checking out the latest in advanced storage and other systems.

"We're pretty aggressive about embracing new technology, especially for our large and medium enterprise customers," Nardi says.

The company uses Fibre Channel-based storage-area networks (SAN) and Gigabit Ethernet-switched disk drives, and it's even exploring iSCSI to stay ahead of the technology curve.

But a specific technology is never the most important issue, Nardi explains. "Users don't pay for a particular disk configuration," he says. "They pay for capacity, reliability and performance."


Future Contenders

These technologies could eclipse Fibre Channel for storage connectivity in the next few years:

iSCSI: Under this draft specification from Cisco Systems Inc. and IBM, SCSI codes are generated from user requests and the data is encapsulated into IP packets for transmission over an Ethernet connection. It overcomes SCSI’s latency problem and 50-meter distance barrier but may have security risks.

Fibre Channel over IP (FCIP): Developed by the Internet Engineering Task Force, FCIP enables the transmission of Fibre Channel information by tunneling data between SANs over IP networks. It’s especially suited for data sharing over a geographically distributed enterprise.

Internet Fibre Channel Protocol (iFCP): This hybrid technology is a version of FCIP that moves Fibre Channel data over IP networks using the iSCSI protocols. It’s designed to interconnect existing Fibre Channel SANs.


The University of Utah in Salt Lake City doesn't have paying customers with penalty-laden service-level agreements, so it can push the envelop a bit further than even technology-rich service providers. It's currently piloting eight SCSI-based storage systems that send block-level data over Ethernet using IP—an approach known as iSCSI.

"It's up to your imagination to come up with creative ways to play with this," says Brian Haymore, the school's senior systems engineer. "Most people already run Ethernet and SCSI, so all you're doing is combining those two pieces together."

The university's iSCSI boxes, which were developed by 3ware Inc. in Mountain View, Calif., each have 650GB of capacity and data transfer rates of about 65MB per second, while comparable Fibre Channel boxes offer gigabit speeds, Haymore says. The iSCSI box, called Palisade, lists for $24,000.

Haymore says the only significant problem he's encountered in using Ethernet as a data storage subnetwork is the latency, about 75 microseconds due to the TCP/IP stack. "If you're digging through thousands of files, that becomes pretty severe," he says.

Haymore considered a Fibre Channel SAN, but he says it was too expensive and he had concerns about its reliability.

He protects the data going over the school's IP network by masking the switched network from the rest of the school's intranet. But Haymore understands there could be security issues with that approach.

"No one knows what the security risks of having iSCSI traffic exposed to anyone else will be yet," he says.

Brian Berg, principal of Berg Software Design in Saratoga, Calif., says iSCSI poses major security problems right now. "You're dropping your drawers unless you have encryption using iSCSI today," he says. "Without an engine to off-load the TCP/IP protocols, performance will suffer with iSCSI." He also claims that iSCSI is inherently less reliable than SCSI or Fibre Channel, too.

Even with those drawbacks, iSCSI remains attractive because it takes standard SCSI data and commands, wraps them in TCP/IP packets and whisks them across the Internet, thus breaking SCSI's 50-meter distance barrier for backup and recovery while still using a common communications protocol.

In addition, most IT professionals are familiar with Ethernet networking, and iSCSI appliances are "plug and play," meaning they can simply be connected to an existing intranet. Additionally, TCP/IP will automatically load-share where multiple connections exist, it retries when it fails to make a connection, and it provides automatic fail-over capabilities. The Internet Engineering Task Force is currently reviewing the proposed storage over IP standards and is expected to finalize them by the end of this year.

But Fibre Channel devotees aren't standing by idly. FCIP is another tunneling technology that lets islands of Fibre Channel SANs interconnet over IP-based networks. This forms a single, unified Fibre Channel SAN fabric for backup or mirroring or to create a more extended Fibre Channel storage network.

FCIP uses a device, such as a switch or router, to wrap Fibre Channel data frames into TCP byte streams or packets. Once the data reaches its target, the TCP frames are stripped off and you again have a Fibre Channel data frame for storage or access.

Another Fibre Channel-based approach is the proposed Internet Fibre Channel Protocol (iFCP). IFCP is designed to interconnect existing Fibre Channel SANs by associating an IP address with Fibre Channel end devices. Every Fibre Channel device in an iFCP network has a unique address that is used to locate the target for the data.

"That is very useful for diagnostics and tracking conversations across a network," says John Webster, a storage analyst at Illuminata Inc. in Nashua, N.H.

Analysts believe iSCSI, iFCP and FCIP will all hit the market, "but that doesn't mean they'll be a commercial success," says Arun Taneja, an analyst at market research firm The Enterprise Storage Group Inc. in Milford, Mass.

Mike Anderson, vice president of information services at The Home Depot Inc. in Atlanta, says he wants to see market adoption and maturity in a product line before he'll buy it.

Anderson helps manage 60TB of data on a centralized architecture. He says there's promise in using a local IP network for real-time data replication for purposes of backup and disaster recovery. "We don't have a redundant data center that does real-time backup right now," he says.

He adds that there's an advantage in networking with IP because of its maturity and standardization.

"The things we think about when managing disks are: Can we share it among multiple operating systems? IP works across all operating systems," says Anderson, whose centralized data center in Atlanta runs on OS/390, Unix, Windows NT and Novell.

So Long, Fibre Channel

In less than seven years, IP storage will dominate over Fibre Channel SANs because of simplicity, the desire for single networks and the technical skills available in the marketplace, says Bob Zimmerman, an analyst at Giga Information Group Inc. in Cambridge, Mass.

But the ability to build an iSCSI-based SAN comparable to today's Fibre Channel SANs won't be a reality until late next year or early 2003, analysts say. For that reason, hybrid tunneling and translation technologies like FCIP and iFCP, which connect Fibre Channel to IP networks, are expected to be around for some time.

Depending on which industry research firm you ask, 3% to 10% of the world's enterprise-class storage is on a Fibre Channel SAN. Because Fibre Channel technology is quickly maturing, along with the tools to manage it, the market share for Fibre Channel networks is expected to grow to 25% within the next two years.

Then there are those who believe that InfiniBand will eclipse Fibre Channel and all of its other supposed replacements. InfiniBand was designed as a replacement for the PCI bus inside servers and PCs in a cooperative effort by Intel Corp., Sun Microsystems Inc., Hewlett-Packard Co. and other industry giants.

Although barely off the drawing board and celebrating just its first year as a specification this month, InfiniBand has generated enormous enthusiasm because it not only replaces an internal bus with an external fabric network, but also can put storage on the same level as cache memory. That leaves all other protocols in the dust in terms of performance.

Still, InfiniBand is years away from being a true alternative to Fibre Channel. Even a backer of the technology, Eyal Waldman, CEO of InfiniBand chip maker Mellanox Technologies Ltd. with headquarters in Santa Clara, Calif., and Yokneam, Israel, says not to expect InfiniBand-equipped servers and storage devices "in the millions" until sometime in 2004.

But when they do get here, Waldman says, you can forget about iSCSI and other Fibre Channel replacements. "They can't scale or give the same price-performance of InfiniBand," he says.

Copyright © 2001 IDG Communications, Inc.

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