Diagnosing problems in a switched fabric

Devices can be connected to processors via a switched fabric, which consists of one or more FICON® directors in the path from the processor (channels) to the device (control unit). The directors may be a long distance from each other and connected via one or more inter-switch links (ISLs). Switch vendors support a number of different fabric topologies and routing algorithms. The path an I/O request takes through the fabric will vary depending upon the fabric topology and routing algorithm. Therefore, when a problem occurs it can be difficult to determine the cause.