Scalability is one of the key features that distinguish the AWS cloud model from traditional data centers or on-premises infrastructure. It refers to the ability to rapidly adjust system resources either through vertical scaling (increasing the size of an instance) or horizontal scaling (increasing the number of instances). It involves growing and shrinking resources to meet the demand of your application and is an essential topic covered in the AWS Certified Developer – Associate (DVA-C02) exam.
The possibilities for scaling in AWS are virtually limitless. Large, multi-billion-dollar corporations can run major workloads in the same AWS infrastructure as small startups with only a handful of customers.
AWS Auto Scaling
A prominent formation of scalability can be witnessed through AWS Auto Scaling. It enables you to set the conditions for when to add or remove resources and it functions across multiple services to deliver scalable responses.
AWS provides Auto Scaling to automatically adjust capacity to maintain steady, predictable performance at the lowest possible cost. Auto Scaling lets you build scaling plans that automate how groups of different resources respond to changes in demand.
For example, if the CPU utilization of your EC2 instances goes beyond 70%, Auto Scaling can automatically launch a new instance to distribute the load.
Below is a simple AWS CLI command for creating an 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 –desired-capacity 3 –vpc-zone-identifier subnet-0bb1c79de3EXAMPLE
Amazon EC2 and Scalability
AWS EC2 instances play a significant role in scalability and are a major focus in the DVA-C02 exam. They come in various sizes and capacities to suit different workloads and can be scaled up (increasing the instance size) or out (adding more instances) based on the requirements.
Here is a comparison table of a few general-purpose EC2 instance types to demonstrate their diversity:
| Instance Type | vCPU | Memory (GiB) |
|---|---|---|
| t2.micro | 1 | 1 |
| t2.small | 1 | 2 |
| t2.medium | 2 | 4 |
Amazon RDS and Scalability
AWS offers the Amazon RDS to make it easier to set up, operate, and scale a relational database in the cloud. It provides cost-effective and resizable capacity while automating time-consuming administration tasks such as hardware provisioning, database setup, patching, and backups.
On Amazon RDS, you have two major ways of scaling: vertical and horizontal.
Vertical Scaling: This involves increasing the instance size. RDS supports various instance types, and you can easily increase the instances size based on your application’s needs by simply modifying the instance and selecting a larger instance type, then allow the modification to be applied either immediately or during your specified maintenance window.
Horizontal Scaling: It involves adding more instances to a database. A Read Replica feature in RDS can be leveraged for horizontal scaling. It allows you to create one or more read replicas of a given source DB Instance and serve high-volume application read traffic.
Understanding AWS scalability and applying it accurately can immensely improve system performance and efficiency and is a crucial part of the AWS Certified Developer – Associate (DVA-C02) exam. AWS’s capacity to implement scalable applications gives room for smaller startups to compete with larger corporations, offering a multitude of opportunities.
Practice Test
True/False: Scalability refers to the ability of a system to handle increased usage and demand without decreasing performance or losing functionality.
- True
Answer: True
Explanation: Scalability refers to a system’s ability to handle an increased load of work or its potential to be enlarged to accommodate that growth.
In terms of AWS, which of the following options offer scalability options?
- A. Amazon EC2
- B. Amazon S3
- C. Amazon VPC
- D. AWS Lambda
Answer: A, B, D
Explanation: Amazon EC2, S3, and Lambda all offer scalability options allowing services to increase or decrease based on demand.
True/False: Automatic scaling can’t be enabled in AWS ELB (Elastic Load Balancer).
- False
Answer: False
Explanation: ELB does support automatic scaling patterns based on specified conditions for managing and scaling your applications.
The process of adding more instances to handle increased load is known as?
- A. Vertical Scaling
- B. Horizontal Scaling
- C. Diagonal Scaling
- D. None of the above
Answer: B. Horizontal Scaling
Explanation: Horizontal scaling means adding more machines or instances into the pool of resources, whereas vertical scaling refers to adding more power to an existing machine.
True/False: AWS provides Managed Databases service which automatically takes care of scalability.
- True
Answer: True
Explanation: AWS Managed Databases, such as Amazon RDS, handle time-consuming database administration tasks including scaling to meet the needs of the applications.
Which AWS storage service automatically scales to store and retrieve any amount of data at any time from anywhere?
- A. Amazon Elastic File System
- B. Amazon S3
- C. Amazon Glacier
- D. All of above
Answer: B. Amazon S3
Explanation: Amazon S3 provides a simple and scalable object storage for data backup and recovery, archive, analytics, and much more, where scaling is managed by AWS itself.
In AWS, the process of increasing or decreasing the compute capacity of your applications is known as?
- A. Load Balancing
- B. Sharding
- C. Auto Scaling
- D. None of the above
Answer: C. Auto Scaling
Explanation: Auto Scaling in AWS helps you ensure that you have the correct number of EC2 instances available to handle the load for your application.
Which AWS service provides real-time data processing over large, distributed data streams?
- A. Amazon Redshift
- B. AWS Glue
- C. Amazon Kinesis
- D. None of the above
Answer: C. Amazon Kinesis
Explanation: Amazon Kinesis makes it easy to collect, process, and analyze real-time, streaming data so you can get timely insights and react quickly to new information.
True/False: Horizontal scaling is always better than vertical scaling in terms of cost effectiveness.
- False
Answer: False
Explanation: It depends on specific business requirements and use-cases. Sometimes vertical scaling is more cost effective than horizontal scaling.
True/False: AWS Lambda supports automatic scaling.
- True
Answer: True
Explanation: AWS Lambda automatically scales applications in response to incoming request traffic. You are only charged for the compute time consumed.
Interview Questions
What does scalability refer to in AWS context?
Scalability in AWS refers to the ability of a system to handle an increasing amount of work by adding resources to the system. This can be achieved either by adding more resources, such as hardware, to a single node (vertical scaling) or by adding more nodes (horizontal scaling) to the system.
What is Auto Scaling in AWS?
Auto Scaling in AWS helps you maintain application availability and allows you to dynamically scale your Amazon EC2 capacity according to the conditions you define. This allows applications to achieve better fault tolerance, handle variable workloads, and optimize costs.
Which AWS tool can you use for horizontal scaling?
AWS provides several tools for horizontal scaling, but the main service used is Amazon EC2 Auto Scaling.
What are some of the benefits of vertical scaling in AWS?
Vertical scaling can improve performance by adding more power to an existing instance. It often requires downtime while new resources are being allocated, but it doesn’t introduce the complexity of distributing and synchronizing data across multiple nodes.
Name two AWS services that help with scalability?
Two common AWS services that help with scalability are Amazon EC2 Auto Scaling and AWS Elastic Beanstalk. EC2 Auto Scaling adjusts capacity to maintain steady, predictable performance, while Elastic Beanstalk is an easy-to-use service for deploying and running applications.
Can Auto Scaling be used with Spot Instances?
Yes, Auto Scaling can be used with Spot instances. When defining the launch configuration, you choose ‘Spot’ instead of ‘On-Demand’ instances.
What is the purpose of a Target Tracking Scaling Policy in AWS Auto Scaling?
A Target Tracking Scaling Policy is a type of dynamic scaling policy in AWS Auto Scaling that adjusts the capacity based on specified dynamic conditions. The purpose is to maintain the target value for the specified metric.
Which AWS service is best used for database scalability?
Amazon RDS (Relational Database Service) is commonly used for database scalability. It allows you to scale DB instances up or down to meet capacity requirements.
What is meant by Elasticity in AWS?
Elasticity in AWS refers to the ability to adapt quickly to workload changes by provisioning and de-provisioning resources in an autonomic manner. It enables services to expand and contract resources in accordance with the demand.
What happens when your load balancer scales?
When your load balancer scales, it automatically adjusts its capacity based on the incoming traffic and the demand of your applications. It distributes the incoming application traffic across multiple targets, such as EC2 instances, that can handle the load.
How does Amazon RDS handle scalability?
Amazon RDS allows you to scale your DB instances up or down to meet capacity requirements. You can manually modify the instance to increase or decrease storage, or you can set it up to automatically scale based on demand.
Why is scalability important in cloud computing?
Scalability is fundamental in cloud computing because it enables the system to handle increasing workloads by adding more resources or more powerful resources. This allows businesses to support their growth and handle large traffic spikes without a major upfront investment.
Can I use AWS Lambda for scalable applications?
Yes, AWS Lambda is a serverless compute service that lets you run your code without managing servers, making it an excellent option for scalable applications. It automatically scales your application by running code in response to each trigger.
Can Auto Scaling increase instances indefinitely?
No, Auto Scaling does not increase instances indefinitely. The user configures maximum limits to prevent incurring high costs due to an uncontrolled increase in instances.
How does AWS S3 contribute to scalability?
AWS S3 (Simple Storage Service) contributes to scalability by providing virtually unlimited storage space. You can store and retrieve any amount of data at any time from anywhere on the web, allowing applications to scale without worrying about storage constraints.
extutorials.com