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I have 2 metrics for my Instances attached to my Load balancer and Auto Scaling Group, one to scale instances up based on CPU Utilization and one to scale down.

My scaling up one works fine whereas the scaling down Instances when under 40% CPU Util seems to work by the alarm being "In Alarm" and it having <40% CPU, it removes 1 Instance as it should but after that it doesn't react taking more than 1 Instance down and I have left it like this for up to 7minutes with just the 1 instance being taken down.

Any idea why it might be doing this?

asd32324
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  • See: [Scaling cooldowns for Amazon EC2 Auto Scaling - Amazon EC2 Auto Scaling](https://docs.aws.amazon.com/autoscaling/ec2/userguide/Cooldown.html) – John Rotenstein Aug 27 '21 at 23:00
  • So since I am using a Simple Scaling Policy there is just a cooldown when removing Instances, odd how it doesn't do this when launching Instances too. – asd32324 Aug 28 '21 at 00:13

1 Answers1

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You can set below to 180 minutes

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you can also set the below 2 settings. but ensure these 2 must be the same

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Health check grace period -> this tells auto calling that after EC2 instance lunch, please wait for x minute so that ec2 instance can setup everything

Default cooldown -> it waits for 300 seconds before triggering the next check

Nimantha
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helper
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