What is Fabric Priority?

Applies to

• Brocade Gen 5-7 Products
• Qualified fabrics include solutions from HBA partners

Answer

• Fabric Priority is an Application Driven QoS (Quality of Service) that:

  • Translates application importance into Fabric Priority

  • Persists priority levels across fabric to end devices

  • Allows End to End priority preservation

• Fabric Priority is assigned via an integer that is associated with a given priority level. 

  • This identifier is incorporated into the header of a typical FC frame, the priority value that is associated with a given I/O path can be reported, end-to-end. 

  • The initiator assigns the priority value for a given frame queue, and the target will then utilize any host-assigned identifiers that it receives in its response frames.

• Since the field being utilized for the Fabric Priority integer is the same as the field utilized for the Cisco VMID, these 2 features cannot be used at the same time.

• However, this is not the case for Brocade VMID (Application Header), which can technically be utilized in conjunction with the Fabric Priority feature.

Aside from versioning, no configuration actions are necessary on the NetApp storage device.

Additional Information

• NetApp's target implementation is to track and return Priority value.
• Use Cases include:
  • HBA inserts preconfigured Priority value into frames
    • Emulex ExpressLane
    • Marvell StoreFusion