By: Allison Hope
Beginning with the Emulex 10.2 software release, all current Emulex LightPulse® LPe16002 Fibre Channel (FC) Host Bus Adapters (HBAs) gained a new, FREE feature called Emulex ExpressLane™.
Just like a fast lane to the office, ExpressLane allows for traffic prioritization to specific Logical Unit Numbers (LUNs). For example, ExpressLane can be used to enable flash workloads to be given higher priority over less time-sensitive workloads and traffic, thereby lowering latency, and reducing jitter.
The feature is really easy to set up as it is enabled by default on the ports of the adapter; the administrator only needs to use Emulex OneCommand® Manager to choose a LUN or LUNs to prioritize.
It takes just a simple right click to select the feature. The yellow lightening symbol in the screenshot below shows that it is selected for that LUN.
Once a LUN has been assigned ExpressLane status, the commands for that LUN are flagged as being given priority.
We’ve created this short video to demonstrate how easy it is to improve I/O performance with ExpressLane:
Click here to watch a two-minute ExpressLane video.
The video demo shows the throughput to five LUNs on a LPe16002 port before ExpressLane is enabled. After it is enabled on one of the LUNs, we clearly see nearly double the throughput in the Medusa Test Tools window.
- In addition, ExpressLane can be configured with a quality of service (QoS) value, carried in the header of every I/O frame of a prioritized LUN that can then be prioritized by switch QoS policy.
- The switch takes the prioritization bit, called the CS_CTL (Class Specific Control) bit, from the frame and processes it to ensure the frame is not deprioritized on the switch layer.
- The CS_CTL bit can also be used by storage arrays to prioritize processing at the final layer.
If you are interested in using the Priority field of ExpressLane, please contact your switch and storage vendors for more information on the CS_CTL settings supported by these devices.
