Viewing, Graphing, and Publishing Metrics
Metrics are data about the performance of your systems. By default, a set of free metrics is provided for Amazon Elastic Compute Cloud (Amazon EC2) instances, Amazon Elastic Block Store (Amazon EBS) volumes, Amazon Relational Database Service (Amazon RDS) DB instances, and Elastic Load Balancing. You can also choose to enable detailed monitoring for your Amazon EC2 instances, or add your own application metrics. Metric data is kept for a period of two weeks enabling you to view up-to-the-minute data and also historical data. Amazon CloudWatch can load all the metrics in your account for search, graphing and alarms with the AWS Management Console. This includes both AWS resource metrics and application metrics that you provide.
You can use the following procedures to graph metrics in CloudWatch. After you have completed these procedures, you can then create alarms for a metric. For more information, see Creating Amazon CloudWatch Alarms.