EC2 instance metrics - Amazon Compute Optimizer
Metrics analyzed for EC2 instancesEnabling memory utilization with the CloudWatch agent
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EC2 instance metrics

Metrics analyzed for EC2 instances

Compute Optimizer analyzes the following CloudWatch metrics of your EC2 instances, including instances that are part of EC2 Auto Scaling groups.

Metric Description
CPUUtilization

The percentage of allocated EC2 compute units that are in use on the instance. This metric identifies the processing power that's required to run an application on an instance.
MemoryUtilization

The percentage of memory that's used during the sample period. This metric identifies the memory that's required to run an application on an instance.

Memory utilization metrics are analyzed for EC2 instances with the CloudWatch agent that's installed on them. For more information, see Enabling memory utilization with the CloudWatch agent.
NetworkIn

The number of bytes that's received on all network interfaces by the instance. This metric identifies the volume of incoming network traffic to an instance.
NetworkOut

The number of bytes that are sent out on all network interfaces by the instance. This metric identifies the volume of outgoing network traffic from an instance.
NetworkPacketsIn

The number of packets that are received by the instance.
NetworkPacketsOut

The number of packets that are sent out by the instance.
DiskReadOps

The read operations per second of the instance store volume of the instance.
DiskWriteOps

The write operations per second of the instance store volume of the instance.
DiskReadBytes

The read bytes per second of the instance store volume of the instance.
DiskWriteBytes

The write bytes per second of the instance store volume of the instance.
VolumeReadBytes

The read bytes per second of EBS volumes attached to the instance. Displayed as KiBs in the console.
VolumeWriteBytes

The write bytes per second of EBS volumes attached to the instance. Displayed as KiBs in the console.
VolumeReadOps

The read operations per second of EBS volumes attached to the instance.
VolumeWriteOps

The write operations per second of EBS volumes attached to the instance.

For more information about instance metrics, see List the available CloudWatch metrics for your instances in the Amazon Elastic Compute Cloud User Guide. For more information about EBS volume metrics, see Amazon CloudWatch metrics for Amazon EBS in the Amazon Elastic Compute Cloud User Guide.

Enabling memory utilization with the CloudWatch agent

To have Compute Optimizer analyze the memory utilization metric of your instances, install the CloudWatch agent on your instances. Enabling Compute Optimizer to analyze memory utilization data for your instances provides an additional measurement of data that further improves Compute Optimizer's recommendations. For more information about installing the CloudWatch agent, see Collecting Metrics and Logs from Amazon EC2 Instances and On-Premises Servers with the CloudWatch agent in the Amazon CloudWatch User Guide.

On Linux instances, Compute Optimizer analyses the mem_used_percent metric in the CWAgent namespace, or the legacy MemoryUtilization metric in the System/Linux namespace. On Windows instances, Compute Optimizer analyses the Available MBytes metric in the CWAgent namespace. If both the Available MBytes and Memory % Committed Bytes In Use metrics are configured in the CWAgent namespace, Compute Optimizer chooses Available MBytes as the primary memory metric to generate recommendations.

Note

  • We recommend that you configure the CWAgent namespace to use Available MBytes as your memory metric for Windows instances.

  • Compute Optimizer also supports the Available KBytes and Available Bytes metrics, and prioritizes both over the Memory % Committed Bytes In Use metric when generating recommendations for Windows instances.

Additionally, the namespace must contain the InstanceId dimension. If the InstanceId dimension is missing or you overwrite it with a custom dimension name, Compute Optimizer can't collect memory utilization data for your instance. Namespaces and dimensions are defined in the CloudWatch agent configuration file. For more information, see Create the CloudWatch agent Configuration File in the Amazon CloudWatch User Guide.

Important

All of the CloudWatch namespaces and metric names are case sensitive.

Example: CloudWatch agent configuration for memory collection


{
    "agent": {
        "metrics_collection_interval": 60,
        "run_as_user": "root"
    },
    "metrics": {
        "namespace": "CWAgent",
        "append_dimensions": {
            "InstanceId": "${aws:InstanceId}"
        },
        "metrics_collected": {
            "mem": {
                "measurement": [
                    "mem_used_percent"
                ],
                "metrics_collection_interval": 60
            }
        }
    }
}