There aren’t really very many choices around when it comes to Fiber Channel (FC) switches for clustering systems together, and as we suspected, Sequent Computer Systems Inc has decided to use Santa Clara, California-based Brocade Communications Systems Inc’s two-to-16 port SilkWorm switch to cluster high-end configurations of its NUMA-Q servers (CI No 3,126). It enables multiple gigabit/100Mb Fiber Channel connections. Sequent has already signed to use Emulex Corp’s LightPulse FC-Arbitrated Loop (FC-AL) hub for mid-size and low-end clusters. The hub divides a gigabit of bandwidth between multiple connections and is a cheaper solution, Sequent says. FC-AL is an extension to the gigabit/100Mbps FC protocol enabling FC devices to be daisy- chained. Brocade has previoulsy said it will support FC-AL later in the year, currently it only supports FC point-to-point connections. Sequnet customized a version of Ancor Communications Inc’s FC switch for NUMA-Q prototyping, but never productised the thing. Using SilkWorm, vendors can create networks of servers and storage devices or ‘fabrics’ as Fiber Channel folk like to call them. It’s for creating large NUMA-Q ‘fabrics’ that Sequent has chosen Brocade. Brocade says that unlike a Fiber Channel hub which shares bandwidth out among attached devices, SilkWorm can operate two-way traffic at a sustained 1Gbps from each port. Brocade claims its switch was the first to implement Fiber Channel Class 3 and 4 specifications which provide for connectionless services. Class 1 devices require a dedicated connection be established before data transfer can begin. Classes 3 and 4 begin transmission without waiting to hear back from the device.
