AWS EC2 Tips for Solutions Architects

Amazon Elastic Compute Cloud (EC2) is a fundamental service in AWS that provides resizable compute capacity in the cloud. Understanding EC2 concepts is crucial for the AWS Certified Solutions Architect Associate (SAA) exam. This cheat sheet provides an in-depth review of key EC2 topics, including instance types, networking, pricing, and lifecycle management.

Benefits of Amazon EC2

Elastic Computing: Scale instances up or down as needed.
Complete Control: Full administrative access to instances.
Flexibility: Choose from multiple instance types, OS, and software.
Reliability: High availability and rapid replacement of instances.
Security: Integration with VPC and security features.
Cost-Effective: Pay-as-you-go pricing model.

When to Choose EC2 Over Other AWS Services

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As an AWS architect, selecting the right compute service is critical for building an optimized solution

EC2 is best suited for scenarios requiring full control over the infrastructure, custom configurations, or when specific software dependencies must be met.

Scenarios Where EC2 is the Best Choice

Use Case	Why Choose EC2?	Alternative AWS Service
Hosting Legacy Applications	Some applications require specific OS versions, configurations, or software that cannot run on managed services.	AWS Lambda, AWS Fargate
Custom Machine Learning Workloads	Need to use custom ML frameworks, GPUs, or specialized hardware.	Amazon SageMaker
High-Performance Computing (HPC)	Tight inter-node communication, low latency, and high-speed networking.	AWS Batch, AWS Lambda
Self-Managed Containers	When orchestration flexibility is required, or Kubernetes is used in a non-managed way.	Amazon ECS, Amazon EKS, AWS Fargate
Regulatory Compliance Requirements	Some industries require dedicated infrastructure control and monitoring.	AWS Outposts, AWS Lambda
Gaming Servers	Require low-latency, high-performance, persistent instances.	AWS GameLift
Big Data Processing	Applications such as Apache Hadoop, Spark, or Kafka require control over compute nodes.	AWS EMR
BYOL (Bring Your Own License)	Some software vendors require customers to run applications on dedicated hosts.	AWS License Manager, AWS Dedicated Hosts
Persistent Long-Running Applications	Need full OS control, custom runtime, or long-running processes.	AWS Lambda (for event-driven), AWS Fargate (for containers)

Key Concepts of EC2

1. EC2 Placement Groups

EC2 instances can be placed in the following ways to optimize performance and availability

Type	Description	Pros	Cons	Use Case
Cluster	Places instances close together inside a *single Availability Zone* to achieve *high network throughput and low latency*.	✅ Low latency communication.	🔶Limited to a single AZ, creating availability risk.	I🚀deal for high HPC and big data workloads.
Spread	Distributes instances across *distinct underlying hardware* to reduce correlated failure risk.	✅ Provides high availability by	🔶 Limited to a maximum of 7 instances per AZ.	🚀Suitable for critical applications requiring fault tolerance.
Partition	Spreads instances across multiple partitions within an AZ, ensuring that *groups of instances do not share the same physical hardware*.	✅ Reduces the risk of simultaneous failure for large-scale distributed applications.	🔶More complex setup and management.	🚀Suitable for distributed big data applications (e.g., Hadoop, Cassandra).

2. EC2 Pricing Models

Pricing Model	Description	Example Use Case
On-Demand	Pay per hour/second, best for short-term workloads.	Ideal for development/testing environments.
Spot Instances	Uses spare capacity, up to 90% discount; can be *interrupted.*	Best for batch processing and fault-tolerant apps.
Reserved	1- or 3-year commitment based on *using specific instances type, region and AZ*. Up to 75% discount.	Great for steady-state applications like databases.
Savings Plans	Commitment-based on usage of *certain dollar amount per hour over a 1- or 3-year period*.	Cost-saving option for long-term, consistent usage.
Dedicated Instances	Physically isolated instances in a shared environment.	Suitable for regulatory compliance workloads.
Dedicated Hosts	Entire physical server dedicated to you.	Ideal for BYOL (Bring Your Own License) scenarios.

Dedicated Instances vs. Dedicated Host

Characteristic	Dedicated Instances	Dedicated Hosts	Example Use Case
Enables the use of dedicated physical servers	✅ Yes	✅ Yes	Organizations with strict compliance/security needs requiring isolated infrastructure (e.g., finance, healthcare).
Per instance billing (subject to a $2 per region fee)	✅ Yes	❌ No	Running individual secure workloads without needing an entire physical server. (e.g., SaaS applications)
Per host billing	❌ No	✅ Yes	Running multiple instances on a single host while maintaining full hardware control (e.g., database licensing).
Visibility of sockets, cores, host ID	❌ No	✅ Yes	Software licensing tied to physical hardware, such as Oracle databases that charge per core/socket.
Affinity between a host and instance	❌ No	✅ Yes	Ensuring critical applications always run on the same physical server for performance consistency. (eg., Low-Latency Game Servers)
Targeted instance placement	❌ No	✅ Yes	Workloads requiring predictable performance by assigning specific instances to particular hardware.
Automatic instance placement	✅ Yes	✅ Yes	EC2 automatically places instances for high availability without manual intervention.
Add capacity using an allocation request	❌ No	✅ Yes	Enterprises reserving capacity in advance for scaling workloads as demand grows (e.g., seasonal traffic s

3. EC2 Instance Lifecycle

State	Description
Stopped	No charge for instance, but EBS volumes incur cost.
Hibernated	Saves RAM contents to EBS, retains instance ID.
Rebooted	OS-level reboot, retains all configurations.
Terminated	Instance is deleted; root EBS volume is lost by default.
Recovered	CloudWatch can recover instances from hardware failure.

4. Storage - Amazon EBS & Instance Store

Amazon EBS - is a durable, high-performance block storage that attaches to EC2 instances,It provides persistent storage.

Instance Store - is a temporary, high-performance storage physically attached to the host machine running an EC2 instance

Key Differences: Amazon EBS vs. Instance Store

Feature	Amazon EBS	Instance Store
Persistence	Data persists	Data is lost on stop/terminate
Performance	High, but network-attached	Ultra-low latency, local storage
Volume Type Options	SSD, HDD, Provisioned IOPS	Fixed per instance type
Snapshots & Backups	Supported via EBS Snapshots	Not supported
Cost	Pay for usage	Free (included with some instances)
Ideal Use Case	Databases, boot volumes, persistent workloads	Caching, temporary storage, high-speed processing

How to Choose Between EBS and Instance Store?

If You Need...	Choose
Persistent storage	EBS
High IOPS databases	EBS (io2, io1)
Low-latency, high-speed data access	Instance Store
Scratch disk for processing	Instance Store
Flexible scalability & backup options	EBS
Cheapest storage for infrequent access	EBS (st1, sc1)

5. Instance Metadata and User Data

Instance Metadata

Instance metadata provides information about a running EC2 instance and can be accessed using the /latest/meta-data/

User Data

User data is used to run scripts during the instance boot process and is accessible at

/latest/user-data

User data is often utilized for:

Installing software packages
Configuring the instance upon launch
Running initialization scripts

6. Public, Private, and Elastic IP Addresses

IP Address Type	Description
Public IP	Assigned to instances in public subnets; lost upon stopping instance; free of charge.
Private IP	Retained across reboots; used within VPC for internal communication.
Elastic IP	Static public IP; chargeable when not associated with an instance; can be moved between instances.

7. AWS Nitro System

AWS Nitro is an advanced virtualization system for EC2 instances, designed to improve security, performance, and cost efficiency. It offloads virtualization functions to dedicated hardware, reducing overhead and increasing system performance.

Key features include:

Nitro Cards: Dedicated hardware for networking, storage, and security.
Nitro Hypervisor: A lightweight hypervisor that provides near bare-metal performance.
Nitro Enclaves: Secure isolated environments for processing sensitive data.
Improved I/O Performance: Enables faster network and disk operations.(e.g., 100Gbps , 60 TB)
Bare Metal Instances: Provides direct access to hardware for workloads requiring minimal virtualization.
Increased Security: Reduces attack surface by eliminating unnecessary software components.

Conclusion

Amazon EC2 is a powerful and flexible cloud computing service that is crucial for the AWS Certified Solutions Architect Associate (SAA) exam. Understanding EC2’s networking, pricing, lifecycle, and placement strategies will help you design resilient and cost-effective solutions in AWS.

Pro Tip: Hands-on practice with AWS Free Tier and test scenarios in the AWS Management Console will reinforce these concepts effectively!

For further reading, visit the AWS EC2 Documentation.

AWS EC2 Cheat Sheet: Mastering Compute for AWS Solutions Architects

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