HP Surestore 64 FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availabil - Page 119
Extended-Distance Ports, High-Availability Considerations, 100 km, Con Ports
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Physical Planning Considerations Extended-Distance Ports Through longwave laser transceivers and repeaters or dense wavelength division multiplexing (DWDM) equipment, directors and edge switches support Fibre Channel data transmission distances of up to 100 km at 1 Gbps, or 50 km at 2 Gbps. The extended distance feature is enabled on a port-by-port basis by activating the 10-100 km check box for a specified port at the Product Manager application's Configure Ports dialog box. This feature provides extended distance support using Fibre Channel protocol only, and does not support distance extension using Fibre Channel over Internet Protocol (FCIP) conversion. When a port is configured for extended distance operation, the buffer-to-buffer credit (BB_Credit) value for the port is automatically set to 60. This value provides sufficient buffering to handle frame processing for link distances up to 100 km. When a director or switch port is configured to support extended link distances, the attached device (or attached fabric element) must also support extended distance operation and be configured to use a higher BB_Credit value to maintain link efficiency. If the extended distance feature is enabled for a port that is not installed or does not support extended distance operation, the configuration for the feature is ignored. In addition, a director or switch port configured for extended distance operation cannot transmit broadcast frames to other ports in a Fibre Channel fabric. High-Availability Considerations To provide high device availability, critical servers, storage devices, or applications should be connected to more than one fabric element (director or switch), or to more than one fabric. To determine if dual-connection capability exists for a device, refer to the associated device documentation. To provide high fabric availability, consider the use of multiple fabric elements, multiple ISLs, or redundant fabrics. Refer to "Fabric Availability" on page 104 for additional information. Plan to maintain unused (spare) director and switch ports if port connections must be quickly moved and re-established after a failure. If an individual port or an entire port card fails, optical transceivers or port cards can be removed and replaced, spare port connections identified (through the Product Manager application), and fiber-optic cables rerouted and reconnected while the director or switch is operational. SAN High Availability Planning Guide 119