Suppose I create an ec2 autoscaling group where each instance is protect terminated. Suppose a min of 2 and a maximum of 4, I was wondering what happens if, in presence of a step policy:

  1. There is a scale-out of 4 and then a scale-in: will always 4 instances be present? Or only 2 will be in the autoscaling group while the others are "benched" somewhat
  2. There is scale-out again: will the extra 2 instance be used or other 2 will be created?
  • Don't turn termination protection on for auto-scaled instances. If you want to know what happens you can probably set this up in an hour to test, and it might cost you a few dollars at most and you'd learn a lot doing it - let us know what you find :)
    – Tim
    Jul 5, 2021 at 8:07
  • Actually termination protection is useful if you have a mixed types of instances and you want to avoid one specific type to be terminated....
    – Phate
    Jul 5, 2021 at 8:51
  • Why would you want mixed instance types in your target group? There are some valid reasons, but in most cases similar instance sizes are simpler.
    – Tim
    Jul 5, 2021 at 9:36

1 Answer 1


If all ec2 instances in an Auto Scaling group are protected from termination during scale in, and a scale-in event occurs, its desired capacity is decremented.

The Auto Scaling group can't terminate the required number of instances until their instance scale-in protection settings are disabled.

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