Detecting a Controller Overload

A controller (which is referred to as a node in C-Mode) manages the flow of information between the server and the data, assigning two paths, in case one of the paths fails or is overloaded. For the best levels of performance and availability, every layer of technology must be balanced.

Comparing the Processor Utilization of your Controllers

1.	In the console, double-click the ProcessorUtilization parameter of the first controller for which you need to compare the activity. A graph is automatically displayed in the graph pane.

2.	Select the ProcessorUtilization parameter of the second controller and drag it from the tree view of the Operator tab to the graph. The second parameter is automatically added to the first one to facilitate the comparison. Compare the values to evaluate the workload distribution.

GRAPH_Two_Processor_Utilization

Comparing Controllers Processor Utilization

For example, if the Processor Utilization on one controller goes above 80% while the other controller stays almost idle, it indicates that one of the controllers constitutes a bottleneck for the storage system that could be alleviated by better sharing the load between the controllers.

Administrators should pay close attention to which logical drive is handled by which controller, depending on the activity of this logical drives to be able to reallocate controller to drive I/O activity so that neither controller is overloaded.

Verifying the Controllers Response Time

The ResponseTime parameter of the SEN_NAP_7_CONTROLLER application class, represents the average time it took the controllers to process the read and write requests of the hosts. The higher the ResponseTime goes, the slower I/Os the servers will get. By default, the solution triggers a warning when the controller takes more than 30 milliseconds on average to complete the I/O requests and an alarm when the response time reaches 100 milliseconds.