For the past few years, vendors and industry pundits have been touting the benefits and inevitable dominance of iSCSI. Since becoming an official standard in February of 2003, the technology which links data storage devices over an IP network has yet to dominate the storage industry by any measure, and perhaps is just now beginning to emerge as a serious contender. Why hasn't iSCSI lived up to its early hype? Who is using it today? And, most importantly, what does the future hold for iSCSI?
The Promise of iSCSI
The oft-repeated promise of iSCSI is relatively uniform across many storage vendors and analysts (see What does iSCSI Mean for Your Storage Network?). An iSCSI IP storage network is generally viewed as less complex to implement and maintain than Fibre Channel. There is also a significant cost differential between iSCSI and Fibre channel, though iSCSI currently does not scale to the same performance level as a Fibre Channel SAN.
Tom Joyce, EMC
As opposed to straightforward NAS, iSCSI also holds a significant advantage in that it shows storage as a virtual block-level device, which allows applications to operate under the illusion that the storage space being used is exclusive. This is important for many different types of data-intensive applications.
The question of whether iSCSI was an early victim of hype gets a very different response depending on whom you ask. Some see it as evolving in line with expectations, while others believe that some of the early enthusiasm was misguided.
The True Believers
Tom Joyce, senior director of NAS product marketing at EMC, said he doesn't believe the technology was overhyped, "Over the last year iSCSI, has evolved in line with EMC's expectations," he said.
|Storage Milestones and Predictions|
|1994||First Fibre Channel specification|
|2000||Fibre Channel specification update for 2 Gbps|
|2003||iSCSI specification ratified as a standard|
|2004||IBM 're-introduces' iSCSI to its lineup with its DS 300 product|
|2005||IDC projects that the iSCSI market segment could grow to approximately $2.48 billion|
|2007||iSCSI forecast by Gartner to become dominating SAN attach protocol|
Joyce also said that there is real merit to iSCSI for companies of all sizes. "Today, many customers are beginning their evaluation process," Joyce said. "Over the next year, we'll see iSCSI moving from the evaluation stage into production as a cost-effective way to consolidate more server-based storage into a network storage infrastructure."
Over at Microsoft, Claude Lorenson, technical product manager, Windows Server Division, said that iSCSI is well on its way to eventual dominance. "We have over 1,000 customers using iSCSI in production today," Lorenson told Enterprise Storage Forum. "We do believe the industry analysts who predict that iSCSI will be the dominating attach protocol for SAN by 2006."
A Steady Diet of Fibre Channel
While some pundits have prophesied that iSCSI will quickly replace Fibre Channel, Cisco Systems is not in that camp. "Certainly, there was a great deal of exuberance about iSCSI and the possible impact the technology would have in future SAN designs," said Ed Chapman, senior director of product management for the Cisco MDS 9000.
"However, looking back on it now," Chapman said, "it's clear that much of the hype was misguided, in the sense that iSCSI was seen as the SAN protocol that would quickly replace Fibre Channel. And as the world's leading company for IP networking solutions, I think the storage industry watchers naturally lumped us in that pro-iSCSI category that was espousing the demise of Fibre Channel."
Chapman said that isn't a fair assertion, seeing as Cisco has a history in the storage market of multiprotocol gateways (beginning with their SN5420 Storage Router). "Multiprotocol support has been the hallmark of our flagship SAN switch products, the MDS 9000 Family, which can run Fibre Channel, iSCSI, FCIP, and FICON all on the same switch," he added.
IBM, for its part, may also have jumped the gun somewhat with its early iSCSI products, according to Cindy Grossman, director of disk marketing at IBM Systems Group. "When I go back a couple of years with the offering that we had, I really think we were a little bit before our time. We were also overpriced for the space."
|Tale of the Tape: iSCSI vs. Fibre Channel|
|Storage Technology||Standardization Year||Transfer Rate||Network Topology|
|Fiber Channel||1994, updated in 2000 for 2 GB||1 .06 Gbps to 2.0
Developing 4.0 Gbps
|iSCSI||2003||1 .0 Gbps
Developing 10.0 Gbps
In fact, there wasn't much early interest in IBM's first foray into iSCSI. "What has typically happened with our enterprise storage server is that anytime something comes out, everybody expects it to be on the big high-end premium products first," Grossman explained. "We actually took the approach that if you wanted to attach iSCSI there are gateways in the marketplace that you can use to attach iSCSI to a high-end device and we supported them. We didn't really get much interest."
IBM's approach to iSCSI has changed as the company recognized where the technology best fits in the enterprise. At the beginning of September, IBM unveiled its new IBM Total Storage DS300 product, which it has touted as an entry-level storage device for mid-size businesses. According to Grossman, the new product was driven by customer demand, especially from its xSeries (Intel-based servers) customers. "That's what drove us with this particular device it also drove us to introduce something that had a much lower cost point," she said.
Ed Chapman, Cisco
From IBM's point of view, the environments where iSCSI is being deployed are typically SMBs, although some departments in larger businesses are also adopting iSCSI. EMC agrees that the SMB market is showing interest in iSCSI, but also notes that larger enterprises are showing an interest as well.
"Many larger enterprises are evaluating iSCSI as a complementary solution to network-isolated servers and workgroup-level storage," EMC's Joyce said. "iSCSI also fits well within an enterprise information lifecycle management (ILM) strategy that calls for tiered storage."
Cisco's Ed Chapman said he sees iSCSI as a cost-effective interconnect technology that's relevant for enterprises of all sizes. "Our SAN switching products are designed to be gateways between iSCSI servers and Fibre Channel storage devices such as disk arrays and tape libraries," Chapman explained. "So, our target market for iSCSI are customers who have already made an investment in Fibre Channel SANs and are considering iSCSI as a way to attach lower-cost servers to those SANs."
Chapman said that many customers he's spoken with have a majority of servers that are not attached to a SAN, the primary reason being the prohibitive cost of equipping them for Fibre Channel.
"The beauty of iSCSI is that now storage administrators have a lower-cost option to attach these stranded servers onto their Fibre Channel SANs by leveraging Ethernet technology," Chapman said. "With this multiprotocol approach, customers can now attach more servers onto their SANs." This increases their operational efficiency and their storage utilization rates, since more servers require more disk resources, he said. This all adds up to lowering the total cost of owning storage. "That is why we see iSCSI as a technology relevant for all customers, including high-end enterprises," Chapman said.
The Cisco experience of using iSCSI as an interconnect technology is also something that it shares in part with Microsoft. According to Microsoft's Lorenson, among its customers "usage varies from new, first SAN all the way to a full enterprise Exchange deployments on iSCSI as well as environments where iSCSI is used to connect to existing Fibre Channel resources for the low price band servers."
The Future's So Bright ...
The future of iSCSI remains bright. As more users understand the benefits of the technology and as the performance of the technology itself improves, increased adoption will follow. "Once customers really understand the value proposition for iSCSI," said Cisco's Chapman, "we'll see adoption really take off."
Price and speed are what will move iSCSI forward, according to IBM's Grossman. "What will determine its adoption curve will be the technology curve," she said. "To the extent that they can improve the performance, with 10 gigabit per second and those sorts of things, it will drive higher adoption rates. When iSCSI has comparable performance to Fiber Channel, you will see the adoption increase even more."