A fabric is a logically defined space in which Fibre Channel nodes can communicate with each other. A fabric can be created using just a single switch, or a group of switches connected together. The primary function of the fabric is to receive FC data frames from a source port (device) and route them to the destination port (device) whose address identifier is specified in the FC frames. Each port (device) is physically attached through a link to the fabric. Many models of switches can participate in only a single fabric. Some newer switches have the capability to participate simultaneously in multiple fabrics. Within a fabric, each participating switch must have a unique identifier called its Domain ID. A SAN provides two primary capabilities: block-level storage connectivity from a host to a storage frame or array, and block-level storage connectivity between storage frames or arrays.
In a Fibre Channel SAN, block requests are handled by a Fibre Channel HBA or Host-Based Adapter. A Fibre Channel HBA is a standard PCI or Sbus peripheral card on the host computer, just like a SCSI adapter. For most typical SAN installations, Fabric connect via switches (FC-SW) is the appropriate choice of Fibre Channel topology. Unlike a loop configuration, a switched fabric provides scalability, and dedicated bandwidth between any given pair of inter-connected devices. FC-SW uses a 24-bit address (called the Fibre Channel Address) to route traffic, and can accommodate as many as 15 million devices in a single fabric. Adding or removing devices in a switched fabric does not affect ongoing traffic between other unrelated devices.
No comments:
Post a Comment