ALR0710W The Zero Send Buffer Credit Percentage of port port_name in storage system device_name was found to be measured_value, which violated the defined warning-idle boundary value of boundary_value.

Explanation

Zero Send Buffer Credit Percentage measures the percentage of time during which the port on a DS8000 storage system had depleted its send buffer credits. That is, the percentage of time when the receiving port had no credit to provide to the port on the DS8000 system. Buffer to Buffer Credit is used as a mechanism to enforce flow-control by the fibre channel protocol, and ensures that a transmitting port that is sending data does not overrun the ability of the receiving port to receive that data. The lack of buffer credits has a negative effect on the overall throughput of the port, and can cascade from port to port, causing congestion in the fabric. A threshold is defined on this metric, which can be used to compare the value of Zero Send Buffer Credit Percentage with the defined boundaries for each set of performance statistics collected from the storage system.

A threshold boundary violation occurred. The specified storage system port has a Zero Send Buffer Credit Percentage value that is less than or equal to the warning-idle boundary, but greater than the critical-idle boundary defined for the related threshold.