According to the Cisco AppDynamics Professional Implementer (CAPI) documents, the two symptoms that occur if an AppDynamics Controller is not scaled correctly are:
The Controller’s metric reporting is 7 to 10 minutes behind the current time. (D) This is a valid symptom because the AppDynamics Controller collects, processes, and stores metrics from the agents that monitor the applications, tiers, nodes, and other entities. If the Controller is not scaled correctly, it may not have enough resources, such as CPU, memory,disk space, or network bandwidth, to handle the incoming metrics data. This may result in a backlog of metrics data that causes the Controller to lag behind the current time. The Controller’s metric reporting delay can affect the accuracy and timeliness of the performance analysis and troubleshooting12.
The Controller UI performs slowly. (E) This is a valid symptom because the AppDynamics Controller UI is a web-based application that allows users to access, visualize, and interact with the performance data and configuration settings of the AppDynamics platform. If the Controller is not scaled correctly, it may not have enough resources, such as CPU, memory, disk space, or network bandwidth, to serve the UI requests. This may result in a slow or unresponsive UI that affects the user experience and productivity12.
The incorrect options are:
Snapshots are not available after 2 weeks. (A) This is not a valid symptom because the AppDynamics Controller does not store snapshots for more than 2 weeks by default. Snapshots are detailed records of the execution context and call graphs of the business transactions that are monitored by the AppDynamics platform. Snapshots are useful for diagnosing performance issues and errors, but they also consume a lot of disk space. The AppDynamics Controller automatically purges the snapshots that are older than 2 weeks, unless the retention policy is changed by the user. The availability of snapshots is not affected by the Controller scaling, unless the disk space is exhausted34.
Health rule violations occur more frequently. (B) This is not a valid symptom because the AppDynamics Controller does not cause health rule violations to occur more frequently. Health rule violations are triggered when the performance or availability metrics of the monitored entities exceed the thresholds that are defined by the user. Health rule violations indicate the presence of performance issues or errors in the monitored applications, tiers, nodes, or other entities, not in the Controller itself. The frequency of health rule violations is not affected by the Controller scaling, unless the Controller fails to collect or process the metrics data5 .
The average response times of tiers are higher than normal. © This is not a valid symptom because the AppDynamics Controller does not affect the average response times of tiers. The average response time of a tier is the average time that the tier takes to process the incoming requests from the business transactions that are monitored by the AppDynamics platform. The average response time of a tier is influenced by the performance and behavior of the application code, the infrastructure, the dependencies, and the workload of the tier, not by the Controller itself. The average response time of a tier is not affected by the Controller scaling, unless the Controller fails to collect or process the metrics data .
References:
1: Controller System Requirements - AppDynamics
2: Controller Sizing Guidelines - AppDynamics
3: Transaction Snapshots - AppDynamics
4: Configure Data Retention - AppDynamics
5: Health Rules - AppDynamics
