Amazon EC2 Auto Scaling | Replacing Impaired Instances Flashcards
My EC2 instances are created with Ansible scripts. How do I use Ansible with Amazon EC2 Auto Scaling?
Replacing Impaired Instances
Amazon EC2 Auto Scaling | Compute
You can find out details about using Ansible with Auto Scaling on the Ansible website.
How does Amazon EC2 Auto Scaling replace an impaired instance?
Replacing Impaired Instances
Amazon EC2 Auto Scaling | Compute
When an impaired instance fails a health check, Amazon EC2 Auto Scaling automatically terminates it and replaces it with a new one. If you’re using an Elastic Load Balancing load balancer, Amazon EC2 Auto Scaling gracefully detaches the impaired instance from the load balancer before provisioning a new one and attaching it to the load balancer. This is all done automatically, so you don’t need to respond manually when an instance needs replacing.
How do I control which instances Amazon EC2 Auto Scaling terminates when scaling in, and how do protect data on an instance?
Replacing Impaired Instances
Amazon EC2 Auto Scaling | Compute
With each Amazon EC2 Auto Scaling group, you control when Amazon EC2 Auto Scaling adds instances (referred to as scaling out) or remove instances (referred to as scaling in) from your group. You can scale the size of your group manually by attaching and detaching instances, or you can automate the process through the use of a scaling policy. When you have Amazon EC2 Auto Scaling automatically scale in, you must decide which instances Amazon EC2 Auto Scaling should terminate first. You can configure this through the use of a termination policy. You can also use instance protection to prevent Amazon EC2 Auto Scaling from selecting specific instances for termination when scaling in. If you have data on an instance, and you need that data to be persistent even if your instance is scaled in, then you can use a service like S3, RDS, or DynamoDB, to make sure that it is stored off the instance.
How long is the turn-around time for Amazon EC2 Auto Scaling to spin up a new instance at inService state after detecting an unhealthy server?
Replacing Impaired Instances
Amazon EC2 Auto Scaling | Compute
The turnaround time is within minutes. The majority of replacements happen within less than 5 minutes, and on average it is significantly less than 5 minutes. It depends on a variety of factors, including how long it takes to boot up the AMI of your instance.
If Elastic Load Balancing (ELB) determines that an instance is unhealthy, and moved offline, will the previous requests sent to the failed instance be queued and rerouted to other instances within the group?
Replacing Impaired Instances
Amazon EC2 Auto Scaling | Compute
When ELB notices that the instance is unhealthy, it will stop routing requests to it. However, prior to discovering that the instance is unhealthy, some requests to that instance will fail.
