Types of EC2 instances and their use cases

EC2 instances come in different families (types), each optimized for a specific use case. Choosing the right instance type is crucial for performance, scalability, and cost optimization in AWS.

Types of EC2 Instances and Their Utilities

1. General Purpose Instances

• Examples:t2, t3, t4g, m5, m6i, m7g
• Utility: Balanced compute, memory, and networking resources. Ideal for applications with moderate resource requirements.
• Use Cases:
  • Web servers
  • Small & mid-size databases
  • Development/testing environments

2. Compute Optimized Instances

• Examples:c5, c6i, c7g
• Utility: High-performance processors optimized for compute-heavy workloads.
• Use Cases:
  • High-performance web servers
  • Scientific modeling
  • Batch processing
  • Gaming servers

3. Memory Optimized Instances

• Examples:r5, r6g, x1, x2idn, z1d
• Utility: Provide large memory size relative to vCPU for memory-intensive applications.
• Use Cases:
  • Real-time big data analytics
  • High-performance databases (SQL, NoSQL, in-memory)
  • In-memory caches (Redis, Memcached, SAP HANA)

4. Storage Optimized Instances

• Examples:i3, i4i, d2, h1, im4gn
• Utility: High, sequential read/write access to large data sets, optimized for storage throughput or IOPS.
• Use Cases:
  • NoSQL databases (MongoDB, Cassandra)
  • Data warehousing
  • Hadoop and distributed file systems
  • Large-scale OLAP systems

5. Accelerated Computing Instances (GPU/FPGA)

• Examples:p3, p4d, g5, g6, f1
• Utility: Specialized hardware accelerators like GPUs or FPGAs for parallel computation and graphics-intensive workloads.
• Use Cases:
  • Machine Learning (training/inference)
  • High-Performance Computing (HPC)
  • Video rendering & 3D graphics
  • Genomic analysis
  • Real-time simulations

Key Takeaways

1. General Purpose: Best for balanced workloads (web apps, dev).
2. Compute Optimized: Best for CPU-intensive workloads (batch processing, game servers).
3. Memory Optimized: Best for memory-heavy workloads (databases, big data).
4. Storage Optimized: Best for high storage throughput workloads (NoSQL, analytics).
5. Accelerated Computing: Best for GPU/FPGA workloads (AI/ML, HPC).

EC2 Purchasing Options

1. On‑Demand Instances

• What it is: Pay by the second (Linux) or by the hour (Windows/others) with no long‑term commitments.
• Utility: Full flexibility — launch or terminate instances anytime.
• Best For:
  • Short‑term, unpredictable workloads
  • Development, testing, or proof‑of‑concept projects
  • When application usage patterns are unclear

2. Reserved Instances (RIs)

• What it is: Commitment to a specific instance type and region for 1 or 3 years, with significant discounts (up to 72%) compared to On‑Demand.
• Types of RIs:
  • Standard Reserved Instances: Cheapest, fixed configuration.
  • Convertible RIs: Flexibility to change instance families, OS, or tenancy during term. Lower discount than Standard RIs.
• Payment Options: All Upfront, Partial Upfront, or No Upfront (monthly payments).
• Best For:
  • Steady‑state workloads (always running applications)
  • Core business systems (databases, ERP, large web apps)

3. Savings Plans

• What it is: Flexible alternative to Reserved Instances. Commit to a certain spend per hour (e.g., $10/hour) for 1 or 3 years. Applies automatically to any instance usage.
• Types:
  • Compute Savings Plan: Applies to any EC2 instance in any region, even AWS Fargate and Lambda. Very flexible.
  • EC2 Instance Savings Plan: Applies only to a family within a region (e.g., m5 in us-east-1).
• Best For:
  • Customers wanting RI‑like savings without being locked to a specific instance type/region.

4. Spot Instances

• What it is: Unused EC2 capacity offered at up to 90% discount compared to On‑Demand. Instances can be terminated by AWS anytime with 2‑minute notice.
• Utility: Extremely cost‑efficient for fault-tolerant, flexible workloads.
• Best For:
  • Big data and analytics
  • Containerized workloads
  • CI/CD pipelines
  • Batch processing, rendering, simulations
• Not Good For:
  • Critical applications that can’t tolerate interruptions

5. Dedicated Hosts

• What it is: Entire physical EC2 server dedicated to you. Provides visibility and control over hardware.
• Utility: Best for software licensing (e.g., Oracle, SQL Server) or compliance requirements requiring dedicated hardware.
• Best For:
  • BYOL (Bring Your Own License) compliance
  • Workloads requiring physical isolation

6. Dedicated Instances

• What it is: Instances running on physical hardware dedicated to a single customer, but not single‑tenant per server. You don’t control placement.
• Utility: Provides hardware isolation for compliance needs but with less cost than Dedicated Hosts.

7. Capacity Reservations

• What it is: Reserve capacity in a specific Availability Zone for increased reliability. You pay On‑Demand rates (unless combined with RI or Savings Plans).
• Utility: Guarantees you will always have available EC2 capacity in a particular AZ.
• Best For:
  • Mission‑critical workloads that require guaranteed capacity during spikes
  • Disaster recovery scenarios

Quick Comparison among all EC2 Purchasing Options