As you prepare for the AWS Certified SysOps Administrator – Associate (SOA-C02) exam, understanding how to create and maintain AWS Auto Scaling plans is fundamental. By implementing AWS Auto Scaling, you can ensure that your applications remain available and performant during demand fluctuations without manually adjusting capacities.
I. Understanding AWS Auto Scaling
AWS Auto Scaling is a service that automatically adjusts your AWS resources according to defined conditions to maintain performance at the lowest cost. It provides two types of scalability:
- Horizontal scaling: This involves adding or removing instances to match demand.
- Vertical scaling: This involves changing the size of an instance to cater to increased or decreased workload.
II. AWS Auto Scaling Components
AWS Auto Scaling consists of several fundamental components. Familiarizing yourself with these components will enable you to create and manage Auto Scaling activities with ease.
- Launch configurations: These are templates that an Auto Scaling group uses to launch EC2 instances. A launch configuration includes instance types, AMIs, security groups, and the instance metadata.
- Auto Scaling groups: These serve as logical grouping units for EC2 instances you want to scale and manage collectively.
- Scaling policies: These are rules that define when your Auto Scaling should launch or terminate instances.
III. Creating an Auto Scaling Plan
Creating an Auto Scaling plan involves the following steps:
- Create a launch configuration: Launch configurations describe the instances that will be created.
aws autoscaling create-launch-configuration --launch-configuration-name my-launch-config --image-id ami-0abcdef1234567890 --instance-type t2.micro --key-name my-key-pair
- Create an Auto Scaling group: Once you have a launch configuration, you can create the Auto Scaling group.
aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg --launch-configuration-name my-launch-config --min-size 1 --max-size 5 --vpc-zone-identifier "subnet-012345ab,subnet-67890cd"
- Define scaling policies: These are the rules that will determine when scaling will take place.
aws autoscaling put-scaling-policy --auto-scaling-group-name my-asg --policy-name my-scaleout-policy --scaling-adjustment 1 --adjustment-type ChangeInCapacity
IV. Maintaining AWS Auto Scaling Plans
Maintaining an Auto Scaling plan involves monitoring and making necessary adjustments to the plan based on the application’s performance and needs.
- Monitor your Auto Scaling group: AWS provides tools like Amazon CloudWatch, which keeps track of your resources and application’s performance.
- Adjust group size: Based on the monitoring data, you may need to adjust the group size to meet your application’s demand.
- Update launch configurations: If you have to change the type of instances your Auto Scaling group is launching, you can do so by creating a new launch configuration and then updating your Auto Scaling group to use the new configuration.
By understanding, creating, and maintaining AWS Auto Scaling plans, you can ensure your resources are efficiently utilized and your applications are always available. This not only leads to AWS cost optimization but also smooth operation of your application, ultimately, helping you perform well in the AWS Certified SysOps Administrator – Associate (SOA-C02) examination.
Practice Test
AWS Auto Scaling allows you to set up scale out and scale in policies for your resources automatically.
- a) True
- b) False
Answer: a) True
Explanation: Auto Scaling allows you to automatically adjust the number of EC2 instances in your application up or down, based on demand or a set schedule.
With AWS Auto Scaling, you can only scale up your resources and cannot scale them down.
- a) True
- b) False
Answer: b) False
Explanation: AWS Auto Scaling not only allows you to scale up but also to scale down your resources when the demand decreases.
Auto Scaling group is a fundamental concept within AWS Auto Scaling.
- a) True
- b) False
Answer: a) True
Explanation: Auto Scaling groups contain a collection of EC2 instances that are treated as a logical grouping for the purposes of automatic scaling and management.
You need to manually start the AWS Auto Scaling plan every time.
- a) True
- b) False
Answer: b) False
Explanation: AWS Auto Scaling works automatically once your conditions are defined and does not require manual initiation.
AWS Auto Scaling is not capable of multiple AZ deployments.
- a) True
- b) False
Answer: b) False
Explanation: AWS Auto Scaling can be used with multiple availability zones to achieve high availability and fault tolerance.
Auto Scaling launches instances based on which of the following options?
- a) Desired capacity
- b) Maximum capacity
- c) LifeCycle Hooks
- d) Launch Templates
Answer: d) Launch Templates
Explanation: Launch Templates in AWS Auto Scaling define the configuration of EC2 instances.
Auto Scaling cannot execute based on a schedule.
- a) True
- b) False
Answer: b) False
Explanation: AWS Auto Scaling can execute plans based on a set schedule, providing greater control and flexibility.
AWS Auto Scaling always uses the same instance type for scaling out.
- a) True
- b) False
Answer: b) False
Explanation: AWS Auto Scaling can use a variety of instance types for scaling out, providing versatility and efficiency in resource management.
With AWS Auto Scaling, you can setup scale in and scale out based on a custom metric.
- a) True
- b) False
Answer: a) True
Explanation: You can use Amazon CloudWatch to send alarms to trigger scaling actions and they can be based on Amazon CloudWatch custom metrics.
AWS Auto Scaling supports Amazon EC2, Amazon EC2 Spot Fleets, Amazon ECS tasks, Amazon DynamoDB tables, and Amazon Aurora Replicas.
- a) True
- b) False
Answer: a) True
Explanation: Amazon RDS databases do not support AWS Auto Scaling. Thus, all listed resources are supported by AWS Auto Scaling.
Which AWS service performs health checks to decide whether EC2 instances within an Auto Scaling Group are healthy or not?
- a) Amazon CloudWatch
- b) Elastic Load Balancer
- c) Amazon EC2
- d) Amazon SNS
Answer: a) Amazon CloudWatch
Explanation: Amazon CloudWatch performs health checks and sends alarms to Auto Scaling to take appropriate actions when instances are unhealthy.
Steps of maintaining an AWS Auto Scaling plan doesn’t include:
- a) Monitor your applications
- b) Update AWS Auto Scaling groups
- c) Immediately terminate the faulty instances
- d) Test your AWS Auto Scaling groups
Answer: c) Immediately terminate the faulty instances
Explanation: AWS Auto Scaling will automatically replace the instances that fail health checks.
An Auto Scaling group spans three Availability Zones and currently has 6 running EC2 instances. If the desired capacity of this group is reduced from 6 to 4, how will Auto Scaling reduce the instances?
- a) Randomly terminate instances from any Availability Zone
- b) Terminate instances based on the termination policies
- c) Terminate instances from two Availability Zones
- d) Terminate the oldest instances first
Answer: b) Terminate instances based on the termination policies
Explanation: Auto Scaling uses termination policies to decide which instances need to be terminated when the size of the group is reduced.
Scheduled Scaling and Dynamic Scaling can not work together in AWS Auto Scaling.
- a) True
- b) False
Answer: b) False
Explanation: You can use Amazon Auto Scaling with scheduled scaling and dynamic scaling at the same time to scale your resources based on predictable peaks and variable workloads.
AWS Auto Scaling can be tested without impacting the running environment.
- a) True
- b) False
Answer: a) True
Explanation: Testing and setting up the Auto Scaling is a practice suggested by AWS to understand the effectiveness of Auto Scaling without disrupting the running environment.
Interview Questions
What does AWS Auto Scaling do?
AWS Auto Scaling automatically adapts your AWS resources to maintain performance and meet demand based on predefined policies, health status, and schedules. It helps ensure that you’re using your resources efficiently and maintaining optimal performance at the lowest possible cost.
What is the primary benefit of using AWS Auto Scaling?
The primary benefit of AWS Auto Scaling is that it allows you to automatically scale AWS resources up or down based on demand, which helps optimise costs and performance.
What are the key components of an AWS Auto Scaling plan?
An AWS Auto Scaling plan consists of a target tracking scaling policy, predefined or custom metrics, and adjustment types (scale out or scale in) to determine when and how to adjust the capacity.
How does AWS Auto Scaling work with Amazon EC2 instances?
AWS Auto Scaling increases or decreases the number of EC2 instances in your application’s architecture based on defined conditions. If demand increases, AWS Auto Scaling will automatically add more instances and if it declines, it will reduce the number, helping balance cost and performance.
What triggers an AWS Auto Scaling event?
A trigger to an AWS Auto Scaling event can be a predefined metric such as CPU utilization threshold, number of requests, or it can be a custom metric defined by users.
How can AWS Auto Scaling help to maintain high availability?
AWS Auto Scaling maintains high availability by constantly monitoring the health of applications and automatically replacing any instance that becomes unhealthy or does not pass certain checks.
Can you use AWS Auto Scaling for services beyond EC2?
Yes, AWS Auto Scaling can be used with services like Amazon DynamoDB, Amazon Aurora, Amazon ECS, Spot Fleets, and more.
How does AWS Auto Scaling help in cost optimization?
It helps in cost optimization by only using the resources required based on the demand. This means you won’t pay for idle resources, as you scale down when usage is low.
What does it mean to “cooldown” in the context of AWS Auto Scaling?
A cooldown period in AWS Auto Scaling is a configurable setting that prevents Auto Scaling from launching or terminating additional instances before previous scaling activities take effect.
How does AWS Auto Scaling perform health check of EC2 instances?
AWS Auto Scaling uses Amazon EC2 status checks and Elastic Load Balancer (ELB) health checks to verify the health of EC2 instances. If an instance becomes unhealthy, Auto Scaling launches a new one.
Can you set a maximum limit on the number of instances with AWS Auto Scaling?
Yes, you can set maximum and minimum limits for the number of instances in your AWS Auto Scaling group. This allows you to control cost and ensure that your application has the required capacity.
How are costs determined for AWS Auto Scaling?
AWS Auto Scaling itself is a free service. Costs are determined by the resources it manages. For example, for managing Amazon EC2 instances, you will be billed for the EC2 instances and for any other resources that are associated with those instances.
Can AWS Auto Scaling be used with Spot Instances?
Yes, AWS Auto Scaling can be used with Spot Instances as well, allowing you to take advantage of lower-cost surplus compute capacity.
How can you implement scheduled scaling with AWS Auto Scaling?
With AWS Auto Scaling, you can perform scheduled scaling by setting start and end times for when your application should scale. This is particularly useful for predictable load changes like daily patterns or specific events.
What are predictive scaling policies in AWS Auto Scaling?
Predictive scaling policies use machine learning to predict your expected traffic and preemptively scale out in advance of predicted demand. Predictive scaling can be used in combination with dynamic scaling for more effective capacity management.
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