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Article Resource September 24, 2012

AWS Announces Greater Control for EC2 Auto Scaling

As most users are aware, the AWS Auto Scale default is to terminate instances by age – with the oldest being the first to go. Now, AWS has added a feature that increases user flexibility by allowing users to craft their own termination policies. We recommend that, as a best practice, users review their EC2 and Auto Scale usage to determine if the default policy of first on/first terminated is best for their needs.

See the attached announcement for more information.

We are pleased to announce that you can now configure Auto Scaling policies to determine which Amazon EC2 instances to terminate when decreasing the size of your Auto Scaling groups.

Using termination policies, you now have more control over which instances you prefer to run within your group. For example, you can specify that Auto Scaling should terminate the oldest instance, the newest instance, the instance with the oldest launch configuration, or the instance that is nearest to the next instance-hour. If you use Auto Scaling to balance your instances across multiple availability zones, Auto Scaling will also use these termination policies when an instance must be removed to maintain balance.

By default, Auto Scaling will continue to choose the instance with the oldest launch configuration when decreasing the size of your group. No action is required on your part. You can replace this default policy if you prefer. For example, you may want configure a termination policy that allows you to keep instances that have the most current version of your application, instances that have been running long enough to accumulate more data, or instances that have more time remaining before they use another full instance-hour.

For more information, please visit the termination policies section of the Auto Scaling Developer Guide at:

The Amazon Web Services team

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