Qlogic SANbox 5800V Series, Installation Manual

Page: 44 / 134

2–Planning
Multiple Chassis Fabrics
2-6 59265-02 B
Multiple Chassis Fabrics
Connecting switches expands 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 QLogic 5800V Series switches in a wide variety
of topologies. Transparent routing to a legacy fabric is also possible using
TR_Ports.
You can connect up to six QLogic 5800V Series switches through the XPAK ports,
thus preserving the SFP ports for devices. This is called
stacking . QLogic 5800V
Series switches divide the XPAK port buffer to balance traffic across the
connection. The XPAK ports operate with any standard XPAK interface. You can
also connect QLogic 5800V Series switches with other switches through the SFP
ports in a wide variety of topologies. Consider your topology and cabling
requirements.
Optimizing Device Performance
When choosing a topology for a multiple chassis fabric, consider the proximity of
your server and storage devices, and the performance requirements of your
application. Storage applications such as video distribution, medical record
storage and retrieval, or real-time data acquisition can have specific latency or
bandwidth requirements.
The QLogic 5800V Series switch provides the lowest latency of any product in its
class. 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 under the
following conditions:

Heavy I/O traffic between specific server and storage devices.

Distinct speed mismatch between devices such as the following:

An 8-Gbps server and a slower 4-Gbps storage device

A high performance server and slow tape storage device
For specific information about latency, refer to “Performance” on page 2-3 .