Electronic Design

FC Port Bypass Controller Elevates SAN Equipment

Slashed costs, parts count, and power consumption along with a boost in performance are the ammunition Fibre Channel PBCs provide SAN equipment.

The Fibre Channel (FC) optical networking standard remains the king in the storage-area-networking (SAN) field. Despite the challenge being made by iSCSI (Internet scuzzy), which uses 1- or 10-Gbit/s optical Ethernet, FC is still the favorite as SAN equipment manufacturers improve speeds and lower costs.

The topology of FC is a ring or loop. FC connects RAID (redundant array of independent disks) or JBOD (just a bunch of disks) to servers or other computers over fiber-optic cable. Speeds have increased over the years to 1.0625 Gbits/s (1G) and 2.125 Gbits/s (2G). Today, over 90% of new systems sold support the 2G speed. In the works are 4G and 10G speed versions.

PMC-Sierra’s FC port bypass controllers (PBCs) significantly upgrade SAN equipment. The 18-port PM8368 PBC 18x2G and the four-channel PM8372 PBC 4x2G can run at either the 1G or 2G speed levels. Each device improves performance, reduces costs, reduces parts count by up to 60%, and cuts power consumption up to 70%, while offering many desirable features and benefits. The PBC-18x2G shown in the illustration contains a 19x19 cross-connect switch that permits maximum flexibility in configuring the 18 ports to the application. The 19th port connects a test-pattern generator and comparator to any of the attached drives for testing.

Each port has it own receiver retimer, transceiver control, and SERDES/repeater to permit retiming, reclocking, and signal pass-through. To ensure high signal integrity with different cable lengths, each port can be programmed with four levels of preemphasis, three levels of receive equalization, and two levels of output swings. The SERDES exceeds industry FC jitter specs. The cross-connect switch supports unlimited disk zoning, making it possible to restrict access for selected disks.

Each port or disk zone can be configured to monitor and measure errors with user-configurable thresholds. The devices monitor CRC32 errors, 8B/10B code violations, comma density errors, and loss of signal. Extensive link and system diagnostics detect and isolate almost any problem or failure so the system can be reconfigured on-the-fly.

The PBC 18x2G and PBC 4x2G are available now for $65 and $21, respectively, in 1000-unit quantities.

PMC-Sierra Inc.
www.pmc-sierra.com/storage

Drill Deeper 4215

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