CPU metrics cannot be selected below 1 minute in Cloudwatch service. For example, how can I lower this period time to trigger the Autoscale scale faster? I just need to trigger the AutoScale instances in short time. (By the way, datapoints value 1 to 1)

CodePudding user response：

the minimum granularity for the metrics that EC2 provides is 1 minute.

Source: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/viewing_metrics_with_cloudwatch.html

Would also say that if you need to scale that quickly, wouldn't the startup time be an issue anyway?

CodePudding user response：

You are correct -- basic monitoring of an Amazon EC2 instance provides metrics over 5-minute periods. If you activate EC2 Detailed Monitoring, metrics are provided over 1-minute periods. Extra charges apply for Detailed Monitoring.

When launching a new instance via Amazon EC2 Auto-Scaling, it can take a few minutes for the new instance to launch and for the User Data script (if any) to run. Linux instances are quite fast, but Windows instances take a while on their first boot due to sysprep operations.

You mention that you want to react to a metric in less than one minute. I would suggest that this would not be an ideal way to trigger Auto-scaling. Sometimes a computer can be busy for a while, then can drop down again. Reacting too quickly to a high CPU load would cause the Auto-Scaling group to flap between adding instances and terminating instances. It is better to provision enough capacity for a reasonable amount of extra load and then gradually add more capacity as it is required over time.

If you have a need to react so quickly, then perhaps you should investigate using AWS Lambda to perform small amounts of work in a highly-parallel fashion rather than relying on Amazon EC2 instances.