The difference between an industry analyst's job and an integrator's job - predicting the future versus making it happen - is seldom so well illustrated as it is in the assessment of storage-area networks (SANs). Jon William Toigo investigatesTo analysts like Dataquest's Tom Lahive, SANs are a slam-dunk: they'll replace traditional server-bus-attached storage within five years in nine out of 10 cases. The technology is simply the best technical and management solution to the problem of skyrocketing distributed-storage needs, analysts say.
For integrators that may be true, but right now SANs - and the Fibre Channel Arbitrated Loop (FC-AL) they're expected to run on - remain a headache. "It will take some time for FC-AL SANs to come down to earth," says Al Lounsbury, director of technology strategy with MCI Systemhouse in Canada.
The game plan for SAN domination isn't exactly clear to storage vendors either, and many of them are the ones with the most at stake. Until vendors figure out where they stand on Fibre Channel SANs, integrators shouldn't expect a lot of clarity or market unity around this new technology. But have no doubt - SANs are coming.
There is little disagreement about which trends are creating the conditions for the rise of SANs. A desire to keep all data sets online and accessible 24 hours a day to an increasingly global and/or Internet-based user population is driving a surge in storage-product acquisitions.
"From now until the year 2000, 75 cents of every hardware dollar spent by companies will be spent on storage," says Bob Pasker, senior vice president with the Yankee Group in Boston.
Yet the primary architecture supporting this growing load - the SCSI-based storage array - is not up to the job. "SCSI is not built for what we want to do today," says Lounsbury. Limited speed, capacity, and physical-configuration options are SCSI's major inhibitors.
FC-AL storage, on the other hand, shatters SCSI's limitations. And with a Fibre Channel-based SAN, instead of connecting a storage array to a specific server, storage resources can be shared among multiple servers and even LANs with the use of a hub or a switch. The SAN can expand as needed using any storage product with a Fibre Channel interface.
It's precisely this "openness" that causes some storage vendors to regard SANs as a threat. "SANs level the playing ground," says AJ Casamento, a "solutioneer" with Fibre Channel switch manufacturer Brocade Communications Systems. "It is clear that this would be frightening to a vendor whose strategy was to enmesh the customer with its products."
According to Casamento and others, the early reluctance of market-leading storage vendors - as well as server vendors that also sell tethered storage arrays - to embrace Fibre Channel SANs was due in part to fears that the technology would erode their market positions. SANs will jeopardise the fortunes of vendors that cannot adapt.
"Large vendors must maintain a very clean and competitive product, or smaller vendors just might replace them in the SAN," says Casamento.
"Once a customer deploys a SAN, his storage options broaden. Many companies are going to discover that they are paying way too much for the storage products they currently use."
EMC marketing manager Doug Fierro bristles at insinuations by network-attached storage proponents that SANs are a commodity replacement for EMC storage products.
Fierro says that assertions that EMC favours proprietary technology over open storage solutions are dead wrong.
"We are the most open storage vendor in the marketplace," he says. "We can connect to NT, Sun Microsystems, and Hewlett-Packard systems simultaneously. We offer storage systems that are like a SAN in a box."
Ditto for Storage Computer's products, says Doug Corrigan, product-marketing manager with the New Hampshire-based company. "Users are looking for data accessibility so they can take data and connect it to multiple hosts," he says. "Products like our StorageSuite family, as well as products from EMC and a few others, have been delivering solutions to address this need for several years."
Still, others disagree. Some even contend that much of the confusion about SANs is derived from misleading claims by traditional storage vendors. "SANs are the hot new technology - a new model catching on in the market, not just another proprietary system," says Bill Lozoff, director of marketing for Gadzoox Networks.
"Some vendors cast their products as SANs to capitalise on the interest in the technology. They legitimise it by pointing out that their product can connect to two or more servers. SANs are more than that. A SAN is an open standard, a network of storage resources that works in a heterogeneous server environment," Lozoff says.
Even if EMC believes its Symmetrix products already provide what customers might want from a SAN, that doesn't mean the manufacturer is ignoring this new storage technology. Fierro says EMC is very interested in the open SAN architecture, which he terms the "enterprise storage network".
Earlier this year, EMC qualified Hewlett-Packard and Sun Microsystems hub products as connectivity options. "We are working toward qualifying other SAN hub and switch products for use with our Symmetrix storage products," says Fierro.
Another traditional storage vendor, StorageTek has also unrolled its official response to SANs. In June, the company announced a global reseller agreement with Brocade Communications regarding a SAN-compatible backup solution. Until native support for StorageTek's SCSI-connected platforms is available, the company is offering "SAN-ready" solutions utilising a SCSI-to-Fibre Channel router.
Some observers question these vendors' motives. In the case of EMC, for example, some claim that support for certain hub products - though a step toward SAN compatibility - may have been driven less by EMC's interest in SANs and more by Sun's stepped-up efforts to displace EMC Symmetrix systems with its own Fibre Channel storage solutions.
The SAN situation is a Catch-22 for storage vendors: they must embrace SANs or else become vulnerable to attacks about offering their own proprietary solutions. But in doing so they set the stage for the replacement of their products by another vendor with less expensive wares.
Fierro concedes that open SANs increase opportunities for other storage vendors in EMC customer accounts.
He argues, however, that EMC products continue to have an edge over those of competitors in the form of superior software intelligence.
"If you look past the component technology being delivered, the real value of the storage product is its software-based capabilities for information sharing, data protection, and storage management," he says. "That is a key differentiator between EMC and other vendors. We have at least a two-to-three year lead in software for the storage arena."
Analysts suggest that SAN technology will become so pervasive over the next three years that the most stalwart stand-alone storage-product vendors have no choice but to buy in.
Most observers agree that until then enterprise storage will continue to comprise a mixture of traditional tethered storage, network-attached models, and SAN solutions.
However, most agree with Gadzoox Networks' Lozoff that the SAN model "will ultimately become the predominant storage technology as companies reach their pain levels with regard to scalability and storage costs".
Brocade's Casamento suggests one sure-fire way to determine whether the pain level is nearing: "I have heard that when an EMC Symmetrix platform is fully loaded with SCSI drives, the weight of the box can exceed the load-bearing capacity of a raised floor. I suppose that when the floor collapses, the need for a new storage architecture becomes pretty apparent."
Pros and cons of Fibre Channel SANs
Like any new technology, the storage-area network still has holes in its resume - but it's nothing that a little salesmanship and creativity can't overcomeProsBigger solutions. SANs based on a Fibre Channel-Arbitrated Loop (FC-AL) can deliver an aggregate storage capacity of 9172GB. The physical loop may extend up to 10km end-to-end, based on 9.1GB drives organised into an array of eight disk drives attached on each node of a 126-node loop. SCSI, by comparison, offers a total capacity of about 136GB per server, with maximum distances between disks and server no greater than 25 metres.
Failover clustering. In a clustered server environment, a SAN provides multiple access paths to the data on the disks, which eliminates the potential for a single point of failure. Achieving the same effect with server-tethered storage requires data replication and hardware redundancy.
Less network traffic. SANs reduce traffic across enterprise networks by handling large file transfers over a separate back-end network - often a boon for companies lacking the bandwidth to accomplish enterprise data backups within ever-shortening time frames.
Tricky data management. It's an oversimplification to think that you simply deploy cable, Fibre Channel hubs and switches, and storage devices to create a SAN. You also need software such as a cluster file system and volume-management package that offers distributed lock management. Current pickings are slim, though many software vendors are busy developing such products.
Unproven standards. Fibre Channel standards are not fully ratified, and the interoperability labs still have a lot of work to do. Important questions remain to be answered, such as how you support directory services in a SAN.
Untested performance. The theoretical capabilities of the 126-node FC-AL are tall, but no one really knows what the actual performance hit will be when a loop is nearly fully deployed. A related issue - still unresolved - is how to prioritise servers so that priority access is granted to storage for critical applications.
SANs turn up the (sales) volume
Video-production houses often get labelled as ideal customers for Fibre Channel storage-area network (SAN) technology. But according to Joe Rorke, vice president of marketing with Rorke Data in the US, audio houses are excellent SAN candidates, too, with one important difference.
"Audio shops can cost-justify a SAN solution in about two seconds," he says. Most of his competitors overlook this fact in favour of targeting the higher-profile video shops - and that's just fine with him.
That leaves more business for Rorke Data, such as the project it's doing for Rocky Mountain Recorders in Colorado.
Like other audio houses that handle sound for motion pictures and music recordings, Rocky Mountain Recorders used to be set up so that each production workstation had its own storage array. Audio files aren't as large as video files, but audio burst-rate requirements - sometimes up to 20Mbps - are typically much higher than those for video, necessitating the dedicated arrays.
The problem with this setup was its inefficiency. In a typical project, engineers had to digitise the audio data using one system and then copy the digital files to the storage associated with each of the other workstations. They then had to copy all changes back to a master file when the work was done.
SAN improves workflow
The SAN that Rorke Data delivered to Rocky Mountain Recorders "introduced a whole new kind of bandwidth opportunity, with no central server hobbling data-transfer rates", says Rorke. That helps save time by streamlining workflow, and it allows engineers to collaborate on projects more easily.
In the past, volume management might have been a problem for SAN storage solutions. Rorke says that his firm's close relationship with Macintosh software vendor CharisMac Engineering has produced a reliable volume-management software solution. Storage on the SAN is expandable in standard configurations ranging to 2TB.
The initial implementation went without a hitch. However, Rocky Mountain Recorders soon decided that it wanted a more advanced hub than the one that was originally provided. "We brought in the Gadzoox Networks' Gibraltar SAN hub to replace a dumb hub from the same vendor," he says. "The customer was happy with the original configuration but just wanted to upgrade immediately to the newer technology."
Know your NAS from your SAN
by Janet Waxman
Storage-area networks and network-attached storage (NAS) are the two hottest trends in the storage market. What you may not know is that these distinct technologies are also the most easily confused by enterprise customers.
The good news, however, is that networked storage presents a new opportunity for system integrators. It's a convergence that inherently creates an increasingly important role for SIs. Companies able to deliver a total enterprise solution - including NAS and SAN expertise - will be sitting pretty. Immediate ROI awaits integrators that seize the day and help enterprise-storage buyers understand and implement their networked options. Many customers will be able to save money by co-locating storage resources, for example; in addition, they will have better and faster access to data through SANs. But, by utilising either NAS or SAN technology, you can help buyers develop a clear, effective road map for storage growth. The key is to know the distinct role of each technology.
SANs are primarily implemented on mainframes or Unix servers whose robust operating systems allow for a single server to perform both application and file-serving functions. SANs don't use a networking protocol, but they do let the storage link directly to the network via an intelligent switch. The result is a direct-connect network limited to its particular set of servers and storage arrays, with high availability and fault tolerance - an environment well suited for mission-critical applications. NAS schemes are more like traditional networks with their use of networking protocols and IP addressing. Storage hangs off the network simply as another device, while file-server applications are performed on a server separate from other applications. A NAS provides a more open environment than a SAN but lacks the high availability and fault tolerance. Unix systems can be found in NAS environments, but typically Unix users are more likely to buy a SAN.
I expect NAS technology to become more sophisticated and fit for critical application areas over time. The next logical step in this convergence of networking and storage will be the partnering of the technologies' respective suppliers. Each party has a piece of the technology and expertise required to complete the solution. Admittedly, the NAS is more dependent on networking technology than the SAN, but each has roles to play.
This transition has been evolving for a while, and with the advent of high-speed I/O technology such as Fibre Channel, the merger of networking and storage technologies has been brought even closer. It will be interesting to see what happens to servers - for years the gateway to network ownership. Now the ante has been raised. Ownership of the network and storage is the new price of admission to the enterprise, with servers becoming more interchangeable. The right application, on a network that includes storage, is the key to today's enterprise.
The challenge will be combining all play-ers into a productive, successful, and non- competitive solution-delivery system.