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Infiniband Bart Taylor
What it is InfiniBand™ Architecture defines a new interconnect technology for servers that changes the way data centers will be built, deployed and managed. By creating a centralized I/O fabric, InfiniBand Architecture enables greater server performance and design density while creating data center solutions that offer greater reliability and performance scalability. InfiniBand technology is based upon a channel-based switched fabric point-to-point architecture. --www.infinibandta.org
History • Infiniband is the result of a merger of two competing designs for an inexpensive high-speed network. • Future I/O combined with Next Generation I/O form what we know as Infiniband. • Future I/O was being developed by Compaq, IBM, and HP • Next Generation I/O was being developed by Intel, Microsoft, and Sun Microsystems • Infiniband Trade Association maintains the specification
The Basic Idea • High speed, low latency data transport • Bidirectional serial bus • Switched fabric topology • Several devices communicate at once • Data transferred in packets that together form messages • Messages are direct memory access, channel send/receive, or mulitcast • Host Channnel Adapters (HCAs) are deployed on PCI cards
Main Features • Low Latency Messaging: < 6 microseconds • Highly Scalable: Tens of thousands of nodes • Bandwidth: 3 levels of link performance • 2.5 Gbps • 10 Gbps • 30 Gbps • Allows multiple fabrics on a single cable • Up to 8 virtual lanes per link • No interdependency between different traffic flows
Physical Devices • Standard copper cabling • Max distance of 17 meters • Fiber-optic cabling • Max distance of 10 kilometers • Host Channnel Adapters on PCI cards • PCI, PCI-X, PCI-Express • InfiniBand Switches • 10Gbps non-blocking, per port • Easily cascadable
Host Channel Adapters • Standard PCI • 133 MBps • PCI 2.2 - 533 MBps • PCI-X • 1066 MBps • PCI-X 2 - 2133 MBps • PCI-Express • x1 5Gbps • x4 20Gbps • x8 40Gbps • x16 80Gbps
DAFS • Direct Access File System • Protocol for file storage and access • Data transferred as logical files, not physical storage blocks • Transferred directly from storage to client • Bypasses CPU and Kernel • Provides RDMA functionality • Uses the Virtual Interface (VI) architecture • Developed by Microsoft, Intel, and Compaq in 1996
Latency Comparison • Standard Ethernet TCP/IP Driver • 80 to 100 microseconds latency • Standard Ethernet Dell NIC with MPICH over TCP/IP • 65 microseconds latency • Infiniband 4X with MPI Driver • 6 microseconds • Myrinet • 6 microseconds • Quadrics • 3 microseconds
References • Infiniband Trade Association - www.infinibandta.org • OpenIB Alliance - www.openib.org • TopSpin - www.topspin.com • Wikipedia - www.wikipedia.org • O’Reilly - www.oreillynet.com • Sourceforge - infiniband.sourceforge.net • Performance Comparison of MPI Implementations over InfiniBand, Myrinet and Quadrics. Computer and Information Science. Ohio State University. - nowlab.cis.ohio-state.edu/projects/mpi-iba/publication/sc03.pdf