Optimizing your AWS infrastructure for cost and performance efficiency is crucial. An important part of this process is adjusting instance types without disrupting operations or incurring downtime. Whether you’re scaling up to meet demand or downsizing to control costs, understanding how to change AWS instance types without downtime ensures uninterrupted service delivery and maximizes resource use.
Below, we’ll cover the most effective methods for changing AWS instance types without downtime and provide our best tips for making the changes smoothly. Read on!
When to change instance types on AWS?
There are several situations where changing instance types can be beneficial:
Performance issues
As your applications expand, their demands for CPU, memory, and other resources may exceed the current instance’s capacity. Upgrading to a more powerful instance can help eliminate these bottlenecks and fine-tune performance.
Troubleshooting and using monitoring tools like AWS CloudWatch are essential for identifying areas where performance falls short. Increasing resource allocation with a higher instance type can prevent issues like slow response times, application crashes, or high latency.
AWS provides AWS Compute Optimizer, which can recommend the best instance type based on your usage patterns. Thus, performance issues and upgrades can be a major cause for changing instance types on AWS.
Cost optimization
Switching to a different instance type can also help optimize costs. Sometimes, you’re provisioning more resources than you need, and downgrading to a less powerful instance type or a different configuration can be a more cost-effective solution.
Using the Amazon EC2 On-Demand Pricing page and AWS Compute Optimizer, you can compare the cost-effectiveness of different instance types.
Application scaling
If you’re experiencing traffic surges or your application demands are high, scaling up to a larger instance type can ensure smooth operation. This is particularly important for applications that are resource-intensive in terms of CPU, memory, or storage.
Auto Scaling Groups can make this process easier, allowing your infrastructure to automatically resize based on traffic. Adding more instances or upgrading to higher-capacity instances can provide the needed scalability to handle increased workload demands.
Changing workload requirements
Different workloads have different resource needs. As your strategy or projects evolve, you might find that a different instance type better suits the new requirements. For example, some applications might need more compute power, while others might require more memory or storage.
By closely monitoring your workload and understanding its specific demands, you can choose an instance type that more effectively supports your application’s performance. This adaptability ensures you’re always using the best configurations for your current needs.
Modernization
As technology advances, AWS releases new EC2 instances with better performance and efficiency. Upgrading to these newer instances can bring significant benefits like advanced features or better hardware capabilities.
This ensures your infrastructure is not only performing at its best but also using the most efficient resources provided by AWS. Investing in modern infrastructure paves the way for improved performance and cost savings in the long run.
Here are the primary methods to change your AWS instance types without suffering any performance hits or operational downtime:
Method 1: Using Auto Scaling groups for reduced downtime
Auto Scaling helps ensure that you have the correct number of EC2 instances available to handle the load for your application. It also has practical benefits, such as allowing for rolling updates to accommodate patching or application updates. Additionally, Auto Scaling groups can manage instance replacements smoothly while maintaining application availability and performance.
To initiate this process, create a new launch template or configuration specifying the new desired instance type(s). Next, associate the new template or config with the existing Auto Scaling group. To apply the changes to existing instances, you can initiate an instance refresh, wait for scaling activities to gradually replace older instances with newer ones, or manually terminate old instances.
When using CloudFormation, the UpdatePolicy attribute specifies how certain updates are handled, e.g., “AutoScalingReplacingUpdate” and “AutoScalingRollingUpdate.” This method ensures high availability and keeps your applications running smoothly without any downtime.
Use cases
Auto Scaling groups are commonly used to horizontally scale application performance. If your application already uses this popular EC2 functionality, then leveraging the instance refresh capability is the best option for engineers to update instance types within an existing Auto Scaling group.
Method 2: Utilizing Elastic Load Balancers (ELBs)
ELBs accept incoming traffic from the clients and route requests to their registered targets, such as EC2 instances, in one or more Availability Zones. Because instances are ‘behind’ the load balancer, traffic can be diverted away from instances slated for modification or upgrade, allowing engineers to systematically replace instances without service interruption.
By registering the new instances (referred to as targets) with the ELB and deregistering the old ones, you maintain seamless application performance and availability.
Use cases
It is ideal for organizations whose application traffic is managed by an Elastic Load Balancer, as is common with many well-architected applications. Their native functionality can easily be leveraged to roll in new application and instance configurations without any downtime or performance impact.
Method 3: Blue/green deployment strategy
This approach involves running two identical environments, one with the current instance type (blue) and the other with the new instance type (green). Traffic is transitioned from the blue instance to the green instance, ensuring a seamless transition.
To create a clone of the existing instance, create an AMI of the source instance. Use the new image to launch an instance with the desired instance family and type. Once the replacement instance is up and running, simply change the association of the Elastic IP address. The EIP association change is seamless, and once the old instance is no longer receiving traffic, it can be stopped and terminated.
Use cases
This method is ideal when there is no Auto Scaling Group (ASG) or Elastic Load Balancer (ELB) configuration in place. Unlike other approaches, a blue/green deployment can replace a single instance rather than a group or cluster. Additionally, this method operates independently of other AWS services.
Tips for changing instance types
Here are a few best practices to make the transition smooth and efficient:
Leveraging elastic IP addresses
Elastic IP addresses play a crucial role when changing instance types, allowing you to move between different instances without affecting external connectivity.
You can associate your existing elastic IP with the new instance type, ensuring uninterrupted service. This method keeps your public IP address intact, making the shift seamless for end-users. Keep in mind that if you use private IP addresses, associate new interfaces with care.
You can also use Elastic Load Balancers (ELB) in conjunction with elastic IPs for more flexibility. This setup distributes traffic to multiple instances, adding a layer of redundancy and performance enhancement.
Test new instance types
Before making your final switch, it’s wise to test your new instance types. Create a staging environment where you can deploy the new instances and apply configurations.
Run your typical workloads to check compatibility and performance to ensure your applications run as expected in the new environment. This step is crucial to avoid unexpected downtimes or performance issues when you change instance types in the production environment.
Testing also helps you validate any scaling procedures, ensuring that auto-scaling groups react correctly to changes.
Monitor performance and costs
Once you’ve implemented the new instance types, you should monitor performance and costs regularly.
Use the AWS EC2 console to track key performance metrics like CPU utilization, memory usage, and network throughput. Pay close attention to your instance state, instance size, and cost fluctuations, as pricing might differ between instance types. Review your billing dashboard and make necessary adjustments to keep costs controlled.
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