BY BRENT ROSS
Not that long ago, many IT organizations were in a quandary about how to handle their accelerating growth of server storage. They probably asked questions and offered responses similar to those that follow:
Q: Why do I need to invest in SAN technology?
Q: Will SAN's help solve my increasing storage management problems?
Q: How soon?
A: Because I need a way to better manage storage growth and deployment.
A: I hope so, but I'm not sure.
A: Soon, and I better start planning.
The only certainty was that in order to move storage into a SAN topology, an investment in Fibre Channel infrastructure and skills was required. Of course, you still had to choose among competing, often non-interoperable Fibre Channel products, especially for a switched-fabric infrastructure.
Consider an IT manager facing those same three questions today. The problems of dealing with the continuous, rapid growth of storage driven by e-commerce and e-communications have proven why we need SANs. The answer to "How soon?" still varies, but everyone is starting to reach a pain threshold. And the introduction of new storage management tools and functionality over the last two years has significantly increased the viability of SAN solutions. The good news is that management problems associated with SAN topologies are now much better understood, and many vendors are working on solutions.
Now there is a fourth question confronting end users who are making the decision to invest in SAN technology: "With what fabric should I build my SAN?" For companies planning future SAN deployment, there will be a choice: Fibre Channel or Ethernet/Internet Protocol (IP). The correct choice depends on what the existing IT infrastructure is, what the current skill set is, what skills can be readily acquired, and how urgent the need is for a SAN. Both Fibre Channel and IP Storage have pros and cons.
Which should you choose?
Fortunately, the choice between Fibre Channel and IP Storage networks is not a question of either/or. Companies that need the benefits of SANs today can invest in Fibre Channel technology and continue to use and grow those SANs effectively in the future. Future SAN deployments can be based on either technology, even if the other one has already been deployed within the enterprise. Future network topologies will include a patchwork of Fibre Channel and IP-based SANs that interoperate with each other across WANs and MANs. New standards are now being proposed or in development to allow the use of pervasive IP WANs or new SAN gateway products to link Fibre Channel SANs with each other and with IP SANs.
Additionally, management application support now being developed for Fibre Channel SANs will be extended to support both types of SAN fabrics. Since both SAN fabric technologies are based on the use of encapsulated SCSI device protocols, extending these applications to support both SAN fabrics is expected to happen quickly. In the future, new management application software will be developed to support both fabrics equally. With so much storage networking technology and product choices now being developed, there is only one wrong choice: failing to plan for the pervasive deployment of storage networking technology.
Making the case for...IP Storage
The most fundamental reason that IP Storage is likely to be adopted quickly is that it is based on two mature and pervasive technologies: Ethernet networks and SCSI storage device protocols. Today, one would be hard-pressed to find an IT installation for any commercial business that does not have an Ethernet infrastructure and equipment (routers, hubs, and switches) carrying TCP/IP traffic. Those installations have a trained staff that knows how to manage and maintain IP networks. A vast array of Ethernet equipment and tools from alternative vendors is available today. 1Gbps Ethernet equipment now on the market supports the installed base of earlier (10Mbps, 100Mbps) Ethernet equipment.
In fact, a user buying Ethernet products can be confident they will be compatible and interoperable with equipment from other suppliers. The same cannot be said for Fibre Channel products, however.
Gigabit Ethernet products that can operate over existing Category 5 cabling infrastructure are widely available from multiple vendors today, so companies that want to move to Gigabit Ethernet for communications or storage networking do not have to install new copper cable or fiber-optic infrastructure. An IT manager planning to build a storage network and has not yet installed a Fibre Channel infrastructure must pay to install and manage that new infrastructure in addition to the existing Ethernet one.
The road map for Ethernet is well-defined through 100Gbps, and hundreds of millions of R&D dollars are being invested annually to bring interoperable 10Gbps Ethernet technology and products to market. This will translate into more 10Gbps Ethernet products from more suppliers sooner than will be possible with 10Gbps Fibre Channel. The cost and price leverage resulting from higher volumes can be seen in the price differences between 1Gbps Ethernet and 1Gbps Fibre Channel switches. Fibre Channel switches today can cost more than three times as much per port compared to Gigabit Ethernet switches.
Almost every operating system and application today with attached storage support has robust SCSI device drivers and SCSI device support features. The SCSI command protocol is also used in Fibre Channel to avoid the need to change applications and device drivers supporting the massive installed base of SCSI storage devices.
To sum up the case for IP Storage: Two pervasive, mature technologies (Ethernet and SCSI) with fully interoperable products available from many vendors are combining within the structure of rapidly evolving standards. This will allow users to create storage networks using infrastructure, tools, and skills already in place. An aggressive Ethernet technology road map will enable evolution to 10Gbps and 100Gbps network speeds.
- Based on two mature, pervasive technologies
- Trained staff, skills easily acquired
- Interoperable Ethernet equipment and tools
- Can operate over existing Category 5 cabling
- Only one infrastructure, rather than having to pay for and maintain two separate infrastructures
- Well-defined road map
- Cost and price leverage resulting from high volumes
Today, Fibre Channel products are available from most leading storage and interconnect vendors. If you're a user who has already made an investment in Fibre Channel technology and skills, you've already paid much of the "cost of entry." If you haven't yet made that investment, you have the benefit of all the lessons learned by the earlier adopters.
Fibre Channel was developed specifically to attach servers to storage as efficiently as possible in a variety of topologies. Fibre Channel specifications address the need for scalability, availability, and distance. FC-AL (Fibre Channel-Arbitrated Loop) loops incorporate redundancy, and switched fabrics provide redundancy, alternate path routing, and zoning. For current 1Gbps Fibre Channel technology, peak throughput of 100MBps is achievable. Next-generation 2Gbps technology is coming to market, doubling that throughput, and focus is now shifting to 10Gbps.
Support for Fibre Channel has been built into most storage management applications, and a new class of applications-SAN management-has emerged. Typically, for end-user adoption of any new technology, a wide variety of vendors must bring products to market to provide function, feature, and price competitiveness, allowing users choices and the opportunity to switch vendors. Fibre Channel has achieved the necessary critical mass of alternative products and technology sources.
To sum up the case for Fibre Channel, it is a mature technology with 2Gbps products shipping. Fibre Channel is the only technology available today to build effective SANs with protocols optimized for storage. Storage management applications and SAN management applications supporting Fibre Channel are widely available, with more coming to market soon. And Fibre Channel has achieved critical mass, with a plethora of product options available. Planned technology advancements will make Fibre Channel a viable technology well into the future.
- Cost of entry may have already been made
- Benefit of lessons learned
- Studies, literature, consultants available
- A technology developed specifically to attach servers to storage
- Road map to 10Gbps
- Storage management applications broadly available
- Critical mass
Brent Ross is marketing manager for IP Storage and networking products at Adaptec Inc. (www.adaptec.com) in Milpitas, CA.