eG Monitoring
 

Measures reported by AWSAutoScalingTest

Amazon EC2 Auto Scaling helps you ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application. You create collections of EC2 instances, called Auto Scaling groups. You can specify the minimum number of instances in each Auto Scaling group, and Auto Scaling ensures that your group never goes below this size. You can specify the maximum number of instances in each Auto Scaling group, and Auto Scaling ensures that your group never goes above this size. If you specify the desired capacity, either when you create the group or at any time thereafter, Auto Scaling ensures that your group has this many instances. If you specify scaling policies, then Auto Scaling can launch or terminate instances as demand on your application increases or decreases.

To measure the effectiveness of Auto Scaling, administrators should continuously track the size and state of instances in each Auto Scaling group and determine whether/not the groups automatically expand and shrink in size when the configured thresholds are breached. The AWSAutoScalingTest test makes this evaluation possible!

For each Auto Scaling group, this test reports the minimum and maximum size threshold configured for that group and also the desired capacity specified for the group. Additionally, the test reveals the current number of instances in that group. By comparing the capacity thresholds with the current number of instances, administrators can tell whether/not Auto Scaling is successful in automatically resizing the group based on the demand/configuration. As an Auto Scaling group shrinks and expands automatically, the instances in the group pass through various states - pending state, standby state, terminating state, etc. With the help of this test, administrators can track the state of instances in each group.

Outputs of the test : One set of results for each Auto Scaling group.

First-level descriptor: AWS Region

Second-level descriptor: Auto Scaling group name

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Grp_minsize Indicates the minimum size of this group. Number  
Grp_maxsize Indicates the maximum size of this group. Number  
Grp_desiredCapacity Indicates the number of instances that this group attempts to maintain. Number  
Grp_serviceInstance Indicates the number of instances in currently running in this group. Number This measure represents the number of instances that are currently in the ‘InService’ state.

When Auto Scaling responds to a scale out event, it launches one or more instances. When the instances are fully configured, they are attached to the Auto Scaling group and they enter the InService state.

Instances remain in the InService state until one of the following occurs:

  • A scale in event occurs, and Auto Scaling chooses to terminate this instance in order to reduce the size of the Auto Scaling group.

  • You put the instance into a Standby state.

  • You detach the instance from the Auto Scaling group.

  • The instance fails a required number of health checks, so it is removed from the Auto Scaling group, terminated, and replaced.

This metric does not include instances that are pending or terminating.
Grp_pendingInstance Indicates the number of instances in this group that are in the Pending state. Number When a scale out event occurs, the Auto Scaling group launches the required number of EC2 instances, using its assigned launch configuration. These instances start in the Pending state. pending instance is not yet in service.

This metric does not include instances that are in service or terminating.
Grp_standbyInstance Indicates the number of instances in this group that are in the Standby state. Number Instances in the Standby state are still running but are not actively in service.
Grp_terminatInstance Indicates the number of instances in this group that are in the Terminating state. Number When Auto Scaling responds to a scale in event, it terminates one or more instances. These instances are detached from the Auto Scaling group and enter the Terminating state.

This metric does not include instances that are in service or pending.
Grp_totalInstance Indicates the total number of instances in this group. Number This metric identifies the number of instances that are in running, pending, and terminating states.