Server I/O Infrastructure with InfiniBand
by InfiniCon Systems
|This article (published
here in August, 2001) examines the benefits of applying InfiniBand to create a
centralized server I/O infrastructure, along with the implications of
disaggregating the I/O subsystem from the processor complex. |
To achieve optimal performance in current-generation servers, a dedicated I/O subsystem, typically based on the PCI local bus, must be tightly bound to each processing complex. The InfiniBand architecture, which provides an industry-standard framework for connecting devices via a very low latency, high bandwidth link, enables the creation of a sharable, centralized I/O infrastructure. Multiple next-generation servers can be connected to this I/O infrastructure via InfiniBand links, resulting in many potential benefits, including data center space savings, bandwidth migration, decreased deployment cost, simplified systems management, and improved cable management.
Due to the high cost associated with providing a truly secure and reliable environment for housing computer equipment, maximizing the utilization of data center space is becoming increasingly important. Server density has improved dramatically, and this trend will continue with the introduction of server-blade technology. Applying InfiniBand to create a sharable, centralized I/O subsystem will accelerate this trend by allowing designers to replace the dedicated I/O subsystem associated with each server with InfiniBand connections scaled to meet the bandwidth and reliability requirements of the server. This will enable further reductions in the size of each server, resulting in significantly improved data center space utilization.
In many application environments, the I/O activity generated by a specific server tends to be somewhat uneven. Periods requiring high I/O throughput are generally followed by periods of lower demand. Servers are often configured with sufficient dedicated capacity to handle the peak bandwidth requirements, but this can result in low average link utilization. An important benefit of the shared I/O subsystem approach is that it allows the bandwidth provided by the shared links to migrate to the servers with the highest demand, providing those servers with significantly higher instantaneous bandwidth than would be feasible with dedicated resources, while simultaneously improving link utilization.
In addition to increasing the bandwidth that can be made available to any given server, the shared I/O model can also significantly reduce the total cost of deployment with respect to a server cluster. In high-availability environments, servers often support redundant connections to multiple infrastructures, including the storage area network, the local area network, and sometimes a separate inter-process communication network. While effective in eliminating single points of failure, this can be a costly approach that requires additional dedicated server ports as well as additional infrastructure ports. The centralized I/O model allows the I/O bandwidth to be matched to the requirements of the entire cluster, reducing port count and complexity, with cost savings of approximately 50 percent.
The reduction in port connections results in significant business and technical benefits for CIOs and data center managers as well. Maintaining and growing high-bandwidth data centers has become increasingly complex and expensive. By deploying a sharable I/O infrastructure, data center topologies can be simplified, reducing the amount of equipment to be managed by system administrators. The growing complexity of the data center cabling matrix can also be substantially reduced.
"Companies have spent thousands of man-hours and millions of dollars deploying their existing data center networks. Therefore, solutions involving InfiniBand must be non-disruptive to the current infrastructure, as well as provide compelling benefits with respect to incumbent technologies," explained Philip Murphy, president and co-founder, InfiniCon Systems. "InfiniCon Systems is focusing its development efforts on these types of solutions."
"Our studies show that a great deal of mindshare has been generated about InfiniBand. However, system administrators are wary of 'yet another fabric in the data center,'" notes John Lawler, directing analyst for E-Business Infrastructure at Infonetics Research. "By positioning its first generation of products as an extended system backplane and not a new LAN technology, InfiniCon Systems avoids these potential barriers to adoption."
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