McDATA 4416 manual Multiple Chassis Fabrics, Optimizing Device Performance

Multiple Chassis Fabrics

Multiple Chassis Fabrics

By connecting switches together you can expand the number of available ports for devices. Each switch in the fabric is identified by a unique domain ID, and the fabric can automatically resolve domain ID conflicts. Because the Fibre Channel ports are self-configuring, you can connect switches together in a wide variety of topologies.

Optimizing Device Performance

When choosing a topology for a multiple chassis fabric, you should also consider the locality of your server and storage devices and the performance requirements of your application. Storage applications such as video distribution, medical record storage/retrieval or real-time data acquisition can have specific latency or bandwidth requirements.

The switch module provides the lowest latency of any product in its class. Refer to “Performance” on page 2-4for information about latency. However, the highest performance is achieved on Fibre Channel switches by keeping traffic within a single switch instead of relying on ISLs. Therefore, for optimal device performance, place devices on the same switch module under the following conditions:

•Heavy I/O traffic between specific server and storage devices.

•Distinct speed mismatch between devices

Domain ID, Principal Priority, and Domain ID Lock

The following switch configuration settings affect multiple chassis fabrics:

•Domain ID

•Principal priority

•Domain ID lock

The domain ID is a unique number that identifies each switch in a fabric. The valid domain ID range depends on the interoperability mode:

•When the interoperability mode is Standard, the domain ID can be 97–127.

•When the interoperability mode is McDATA Fabric Mode, the domain ID can be 1–31.

The principal priority is a number (1–255) that determines the principal switch which manages domain ID assignments for the fabric. The switch with the highest principal priority (1 is high, 255 is low) becomes the principal switch. If the principal priority is the same for all switches in a fabric, the switch with the lowest WWN becomes the principal switch.

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McDATA 4416 Fibre Channel Switch Module Installation Guide