A company is migrating a data center from its on-premises location to AWS. The company has several legacy applications that are hosted on individual virtual servers. Changes to the application designs cannot be made.
Each individual virtual server currently runs as its own EC2 instance. A solutions architect needs to ensure that the applications are reliable and fault tolerant after migration to AWS. The applications will run on Amazon EC2 instances.
Which solution will meet these requirements?
To ensure that the applications are reliable and fault-tolerant after migration to AWS, creating an Auto Scaling group with a minimum and maximum of one is effective. This configuration ensures that if an instance fails, the Auto Scaling group will automatically replace it with a new instance, maintaining high availability and reliability. By using an Amazon Machine Image (AMI) of each application instance, you can ensure that any new instance launched will have the same configuration. Additionally, configuring an Application Load Balancer in front of the Auto Scaling group helps manage incoming traffic and prepares for future scaling if needed.
NOT A: Autoscaling with Maximum of 1 EC2 :D NOT B: Hourly backup... RPO 1hr C: AMI, Multi-AZ -> Fault tolerant NOT D: ECS with Fargate, but it needs to run on EC2..
You cannot change application and based on the story in the past there was only one server/copy of application running at the same time. So we cannot run more then one copy of any application at once. It is possible to set Min and Max to 1 which will automatically bring up server when it will crash. Taking into consideration that we cannot change application design and load-balancing between regions would probably need that (no information if applications are statefull or stateless) i would go for solution in answer A
Autoscaling with max=1 is what is needed to keep only one instance at a time - it will still fail, but it will spawn exactly one instance in case of failure (we are not allowed to change the design of the app) Having single instances in different AZ will not help - if one of the AZs is down, the app will still be affected
It's either A or B but A is a better option. The application design cannot be changed so we don't know if it can run across 2 servers.
answer is A. Auto Scaling Group: Explanation: Minimum and Maximum of one instance: Ensures that the instance is always running. If the instance fails, Auto Scaling will automatically replace it with a new one, maintaining high availability. Amazon Machine Image (AMI): Captures the current state of the application instance, ensuring that new instances launched by Auto Scaling will have the same configuration. Application Load Balancer (ALB): Load Balancer: Distributes traffic to the instances in the Auto Scaling group, ensuring fault tolerance. Even though there is only one instance, the ALB can help manage incoming traffic and be ready for future scaling if needed. For C: While this provides high availability, it does not address fault tolerance as effectively as the Auto Scaling group approach. Without Auto Scaling, if an instance fails, manual intervention is required to launch new instances.
A. Create an Auto Scaling group that has a minimum of one and a maximum of one. Create an Amazon Machine Image (AMI) of each application instance. Use the AMI to create EC2 instances in the Auto Scaling group Configure an Application Load Balancer in front of the Auto Scaling group.
Fault tolerance is not High Availability Answer A is HA design, not Fault tolerance
A makes sense. C is possible but manual intervention.
A makes sense
Answer A It is possible to set Min and Max to 1 which will automatically bring up server when it will crash. Taking into consideration that we cannot change application design and load-balancing between regions would probably need that (no information if applications are statefull or stateless) i would go for solution in answer A https://docs.aws.amazon.com/autoscaling/ec2/userguide/asg-capacity-limits.html