"Abomination!" the Jacobins are thundering from the pulpits. "Contrary to Nature!" Or something... Startup Voltaire Inc. has created a weird hybrid to provide storage connectivity to its InfiniBand switch: It's running iSCSI over InfiniBand to let servers access back-end Fibre Channel storage systems (see Voltaire Bonds iSCSI With InfiniBand).
Voltaire is the first IB switch maker to adopt iSCSI, an IP-based protocol for transmitting SCSI storage traffic. The company has also developed a Fibre Channel module for its switch to provide access to existing FC SAN storage. This thing is just begging for a new moniker -- InfibriSCSI, anyone? (Too Polish?)
But it isn't using TCP/IP for the transport layer. Instead, Voltaire is using the low-level Remote Direct Memory Access (RDMA) features built into the InfiniBand protocol. That eliminates the performance bottlenecks associated with iSCSI today, providing very low CPU overhead while reaping the benefits of an industry standard, the company says.
Asaf Somekh, director of marketing at Voltaire, says running iSCSI over InfiniBand eliminates the need for an additional storage adapter in a server that's connected to an IB fabric, instead of requiring a separate Fibre Channel host bus adapter (HBA).
He adds that 4x (10 Gbit/s) InfiniBand delivers roughly five times the aggregate throughput of 2-Gbit/s Fibre Channel. "We're seeing some environments where customers are putting three [Fibre Channel] HBAs in the server because they weren't getting enough throughput," Somekh says. "If you look at the aggregated approach, building on the 4x InfiniBand, you're not limited."