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Reserved Instances, which provide a guaranteed compute capacity and are available at various discounts for long-term commitments and Spot Instances, which provide a spare compute capacity at a very low price, but are only available when your bid price is high enough. Even though they work differently, both provide opportunities to make significant savings if used properly.
In this, the final part of this series, we will discuss AutoScaling groups, a free AWS service that controls groups of instances using various features, and can also be used to reduce overall spending by shutting down unused resources. Let’s look at how it works.
AWS Auto Scaling Groups Overview
AWS Auto Scaling Groups contain a collection of EC2 instances (On-Demand, Reserved, or Spot) defined by the Launch Configurations (templates with defined AMIs, instance types, security groups, etc), that Auto Scaling Groups control in different ways depending on your needs. The basic configuration allows you to choose the desired minimum and maximum number of instances, the load balancer (if any) to be placed in front of them, and which subnet and Availability Zone to run them in.
Auto Scaling Groups can be used to control backend resources behind an ELB, provide self-replication (when the instance crashes, Auto Scaling Group will immediately provision a new one to maintain the desired capacity), simplify deployments (regular releases, blue/green deployments, etc.), and for many other use cases. However, what we are really interested in here is how we can use them to reduce our EC2 spending.
The Issue with Auto Scaling Groups
The unnecessary spending on EC2 instances is usually caused by unused, or underused, compute resources, that increase your monthly bill. This is an age-old problem where you provision more than you need, to make sure you have enough to handle the expected, but also unexpected traffic.
An Auto Scaling Group solves this issue by handling the scalability requirements for you. Let’s say you need compute resources that are serviced by one m4.4xlarge instance. However, looking at the actual CPU usage (CloudWatch metric), you notice that it varies between 20% and 80% during the day. Not very efficient, is it?
The Benefit of Auto Scaling Groups
So how can Auto Scaling Group help? One of the features it provides is Scaling Policy, which allows you to scale resources based on demand. So instead of using one m4.4xlarge instance, you simply create an Auto Scaling Group that has four m4.xlarge instances, and create a policy that will reduce the number of running instance by two when CPU usage is below 50%.
When CPU usage goes below 25%, it will reduce the number of running instances to only one. By using this simple policy (which can be perfected with more fine-tuning), you will ensure that when the demand for compute capacity is low, you will have fewer resources provisioned, thereby reducing the cost.
Why this matters
Moreover, adding a policy to scale back up when demand is higher will create a fully automated environment that can scale dynamically without your intervention. If you have predictable workloads, e.g., peak usage between 1pm and 6pm during the weekdays, you can also use Scheduled Actions to set recurring scaling during the desired time period. This feature is good for scaling down when you know you won’t need compute resources, and also as a pre-emptive scaling up during events such as Black Friday.
Tips
- When you first start creating scaling policies, start small and monitor your scaling activities using Activity History to make sure your policies don’t cause instability in your environment.
- Scale up quickly to meet the demand, and scale down slowly to make sure you don’t remove resources too soon.
- Always scale up and down symmetrically; this will prevent inconsistent scaling, and allow you to have the exact amount of resources that you have planned for.
AWS’ Recently Launched Auto Scaling Feature
In January 2018, AWS launched their brand-new service called AWS Auto Scaling which now allows you to manage DynamoDB, ECS, Spot Fleets and Aurora, in addition to the existing ability to scale in and out EC2 instances. This expansion, to support the management of multiple services – containers, spot instances and databases – allows developers to configure auto-scaling in a single unified interface.
When using this service, keep in mind that the console does require that the user select a Cloudformation stack, therefore all infrastructure must be deployed under a stack. The new service is a great new addition offering developers a way to balance both cost and availability, depending on what their company requirements are.
This new feature is available immediately in US East (Northern Virginia), US East (Ohio), US West (Oregon), EU (Ireland), and Asia Pacific (Singapore) regions.
Summary
Auto Scaling Groups are one of the most utilized services offered by AWS. The ability to self-heal production environments, and to dynamically control them using scaling policies at no additional cost, is simply too good to miss. Auto Scaling groups can also be used together with Reserved and Spot Instances (each providing their own benefit) to maximize the savings you can make on EC2 resources. You simply need to find the best way to incorporate them into your infrastructure.
In this three-part series, we have shown you just some of the ways you can utilize existing AWS services to optimize your spending, and hopefully removed any doubts about the cost of AWS. Of course, there are many more ways to be smart about saving money with AWS, so make sure you do your research and enjoy the full benefits of this public cloud service.
Automating Instance Backup Using N2WS
While using in-house scripts can provide for a basic backup solution, it doesn’t make business sense for organizations to invest in a fully-featured in-house backup solution rather than focusing on their business-critical tasks.
N2WS Backup & Recovery is an enterprise-class backup-recovery and disaster recovery solution designed for AWS EC2 covering all the essential backup and recovery features to ensure robustness of the backup and DR solution as well as simplifying processes and saving precious devops time. N2WS is available as a service model that allows users to manage multiple AWS accounts and configure policies and schedules to take automated snapshot backups. It also has a Windows agent to consistently back up Windows applications.
N2WS allows you to recover a volume from a snapshot, increase its size and switch it with an existing attached volume in a single step. Furthermore, in a dynamic cloud environment, you need to be able to keep consistent backup policy across all your instances at any point in time.