Interview

Getting hooked

Kate Evans-Correia
Can you explain the difference between the three major technologies,Infiniband, IP-storage (iSCSI) and Fibre Channel?
These three technologies are a mixture of hardware and software. Infiniband is an Intel-led effort to develop the next generation system interconnect. Within a system, Infiniband will be a candidate successor to PCI, between systems it will compete with Gigabit Ethernet and 10 Gigabit Ethernet. Infiniband is at the beginning of its growth cycle, with early prototypes becoming available in approximately a year for use within the system. Intersystem communications will come much later. Fibre Channel is the combination of a specialized physical network, low-level protocol, and high-level transfer protocol. It is specialized for storage, and in the past was the only network that could provide high-speed SAN functionality. Now that Ethernet performance has matched, and is about to exceed, the performance of Fibre Channel, there is an alternative to the expensive and exotic Fibre Channel network. Above the Ethernet and TCP/IP networking layers, iSCSI is the proposed IETF (Internet Engineering Task Force) standard protocol for running storage traffic on the dominant industry standard network. With the broad acceptance of iSCSI, which will occur during 2001, Fibre Channel will be superseded by networks based on the industry standards of Ethernet, TCP/IP, and iSCSI. What are the advantages and disadvantages of each?
Infiniband doesn't exist yet,

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and we don't expect it to be broadly available until the middle of 2002. Most vendors today seem focused on Infiniband as a PCI replacement for internal use within a system. Fibre Channel, the most expensive option, does not perform well, or even at all, in environments with mixed vendors switches. In addition, there is a significant lack of technically trained people who know how to configure and manage these complex Fibre Channel SANs. Also, iSCSI leverages widely accepted infrastructure, Ethernet and TCP/IP. It is supported by thousands of people who are well-trained in the deployment and management of these technologies. Finally, the stack of Ethernet, TCP/IP, and iSCSI can be deployed far less expensively than Fibre Channel, particularly in the areas of switches and network routers. What are a few keys concepts that make Infiniband important?
Infiniband will provide a significant increase in bandwidth, when it is adopted. Current inexpensive infrastructures, like PCI, are limiting the throughput of modern systems. What types of specific products could we expect that will incorporate Infiniband technology?
Internal interconnect will be the first, such as RAID cards and NICs, to utilize Infiniband. If it goes external, storage will be a major user. There is a potential for cross box crossbars using Infiniband, but they are far in the future and will require a massive change to the computer infrastructure as we know it. Do you think Infiniband technology will replace Ethernet?
No, not for a very long time, if ever. Ethernet is too widespread and performance is "good enough" for most end users, particularly as the entire Ethernet installed base moves to 1 Gigabit Ethernet this year and then 10 Gigabit Ethernet during 2002. Consider the efforts that have been made to introduce other network technologies like Token-Ring, ATM, and a host of others. Bob Metcalf, the inventor if Ethernet refers to all of these as "Ether-NOT technologies". We feel that Infiniband will have a difficult time ever replacing Ethernet between boxes. It will probably be "Ether-NOT." Is Infiniband supported by any major vendors?
here are lots of them. Check out this Infiniband vendor list. Do these technologies have compatibility issues?
It is far too soon to tell if there are compatibility issues with Infiniband. Because it doesn't exist yet, it has no bugs. Ethernet and TCP/IP have about the best compatibility of any standards in the industry, while Fibre Channel has about the worst. Some Fibre Channel vendors, like Brocade, have even publicly stated that they will not bother being compatible with any other switch vendor. This approach would be wholly unacceptable in a true network, like Ethernet. When is a business likely to use one over the other?
For performance at any cost, Fibre Channel is superior. For flexibility and ubiquity at 80% of Fiber Channel's performance and less than half the cost, then iSCSI is the winning technology. In the future, over two years from now, expect Infiniband to be driven into the market as a PCI replacement. What are the costs associated with implementing these technologies?
Implementation costs of Fibre Channel have already been quite high. Primarily because of the massive incompatibilities that exist within the various products provided to the marketplace. Interoperability testing and development are much more expensive than in industry standard networks, like Ethernet. Infiniband will require a complete rebuild of the internal bus infrastructure, to replace PCI, and the external networking infrastructure, to replace Ethernet. The number of controllers, NICs, and other devices that have to be rebuilt and reprogrammed is massive. Ethernet, by contrast has standard components that are available off the shelf, and with the introduction of iSCSI, and iSCSI ready products like ware's NSU, it is now possible to implement a Storage Area Network as inexpensively as one implements an Ethernet. What about standards?
Fibre Channel clearly suffers from poor standardization. The numerous "Compatibility Fairs" are not a sign of compatibility or interoperability. So, while Fibre Channel claims that there is a standard, the vendors have failed to a find a common working sub-set of the standard the provides interoperability. Infiniband has a proposed standard, to which no one has built a product. iSCSI is a standard about to be approved by the IETF, and supported by a number of vendors including 3ware, IBM and HP.
Related Topics: SAN management, VIEW ALL TOPICS

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