Identify any Amazon EC2 instances that appear to be underutilized and downsize (resize) them to help lower the cost of your monthly AWS bill. By default, an EC2 instance is considered "underutilized" when matches the following criteria (to declare the instance "underutilized" both conditions must be met):
Downsizing underutilized EC2 instances to meet the capacity needs at the lowest cost represents an efficient strategy to reduce your monthly AWS costs. For example, resizing a c4.xlarge-type EC2 instance provisioned in the US-East (N. Virginia) region to a c4.large-type instance due to CPU and memory underuse, you can roughly save $72 per month (as of March 2017).
To identify any underused EC2 instances provisioned within your AWS account, perform the following:
Option 1: Downsize (resize) the underused EC2 instances provisioned within your AWS account. To resize any EC2 instance that is currently running in "underutilized" mode, perform the following commands:(!) Important note: the following process assumes that the EC2 instances selected for downsize are NOT currently used in production or for critical operations. To resize production instances without any downtime, you should create a snapshot of your current image and launch a new instance from that snapshot using the required instance type.
Option 2: Disable the rule check. If the selected underused EC2 instance configuration must remain unchanged (some workload scenarios can result in low resource utilization by design), you should turn off the conformity rule check for the specified instance from the Cloud Conformity console.