Switch AWS Dedicated Tenancy Instances to Shared

AWS has the option for instances to be either dedicated (on their own segmented physical host) or shared (be on the same physical host with other AWS customers). Dedicated tenancy comes at a premium since hosts need to be solely dedicated to a customer’s resources. There is no performance difference between dedicated and shared tenancy instances, the only reason to have dedicated tenancy is to be in compliance with a specialized regulation such as HIPPA. 

If you find yourself accidentally selecting dedicated tenancy these are the steps to switch it to shared, as the AWS console does not currently provide a way to switch tenancy. 

  1. Open up AWS Cloudshell in the AWS console of the account with the dedicated hosts. 
  2. Copy the instance ID(s) of the dedicated instances you wish to switch to shared
  3. Run this command for each in the Cloudshell terminal:
aws ec2 modify-instance-placement --instance-id [ID VALUE] --tenancy default