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2–Planning
Multiple Chassis Fabrics
59229-05 A 2-7
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 QLogic 9000 Series switch provides the lowest latency of any product in its
class. Refer to “Performance” on page 2-3 for information about latency and
bandwidth. However, the highest performance is achieved on Fibre Channel
switches by keeping traffic within a single I/O blade. Therefore, for optimal device
performance place devices on the same I/O blade 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
When planning a fabric, consider how to create redundant paths and minimize
latency. Initiators and targets experience the least amount of latency when
connected to the same I/O blade. For example, connecting initiators and targets
ports together in parallel on two I/O blades, as shown in Figure 2-1, creates
redundant paths and minimizes latency.
Figure 2-1 Single Switch Fabric with Initiators and Targets
Initiators
Targets