AWS Storage Options – CloudFront & ElastiCache

Amazon CloudFront

• is a webservice for content delivery
• provides low latency by caching and delivering content from a global network of 750+ Points of Presence (PoPs) across 100+ cities in 50+ countries
• supports HTTP/HTTPS for static and dynamic content delivery
• optimized to work with Amazon services like S3, ELB, MediaConvert etc. as well as works seamlessly with any non-AWS origin server

Ideal Usage Patterns

• is ideal for distribution of frequently accessed static content, or dynamic content or for streaming audio or video that benefits from edge delivery
• API acceleration and real-time content personalization at the edge
• security at the edge with integrated WAF, DDoS protection, and bot management

Anti-Pattern

• Infrequently accessed data
  • If the data is infrequently accessed, it would be better to serve the data from the Origin server
• Programmatic cache invalidation
  • CloudFront supports cache invalidation, however AWS recommends using object versioning rather than programmatic cache invalidation.

Performance

• is designed for low latency and high bandwidth delivery of content by redirecting the user to the nearest edge location in terms of latency and caching the content preventing the round trip to the origin server
• supports HTTP/2 and HTTP/3 (QUIC) for improved connection performance

Durability & Availability

• provides high Availability by delivering content from a distributed global network of edge locations. Amazon also constantly monitors the network paths connecting Origin servers to CloudFront
• does not provide durable storage, which is more of the responsibility of the underlying Origin server providing the content for e.g. S3

Cost Model

• has pay-as-you-go pricing with two main components:
  • regional data transfer out (per GB) and
  • requests (per 10,000)
• Flat-Rate Pricing Plans (launched Nov 2025) — combine CloudFront CDN, AWS WAF, DDoS protection, bot management, Route 53 DNS, CloudWatch Logs, edge compute, and S3 storage credits into one monthly price with no overage charges

Scalability & Elasticity

• provides seamless scalability & elasticity by automatically responding to the increase or the decrease in the demand

Edge Compute

• CloudFront Functions — lightweight functions for high-scale, latency-sensitive request/response transformations (URL rewrites, header manipulation, redirects) executed at 750+ PoPs
• Lambda@Edge — more powerful compute triggered at regional edge caches for complex logic (authentication, dynamic origin selection, content generation)
• CloudFront KeyValueStore (launched 2023) — globally distributed, low-latency data store for CloudFront Functions enabling dynamic configuration (A/B testing, feature flags, geo-routing) without code redeployment

Security

• Origin Access Control (OAC) — recommended method to restrict S3 origin access to CloudFront only, replacing the legacy Origin Access Identity (OAI). OAI creation was deprecated in 2024; new distributions since March 2026 can only use OAC.
• AWS Shield Standard — included automatically with every CloudFront distribution for DDoS protection at no extra cost
• AWS WAF integration — protect against web exploits and bots at the edge
• Field-Level Encryption — encrypt sensitive data fields at the edge before forwarding to origin

ElastiCache

• is a fully managed, serverless caching service that makes it easy to deploy, operate, and scale distributed in-memory caches in the cloud
• helps improves performance of the applications by allowing retrieval of data from fast, managed, in-memory caching system with microsecond latency and up to 99.99% availability SLA
• supports three open-source caching engines:
  • Valkey (recommended for new workloads) — open-source fork of Redis OSS 7.2, stewarded by the Linux Foundation (BSD-3 licensed)
  • Memcached — simple object caching engine
  • Redis OSS — key-value store (note: Redis OSS 7.2 is the last fully open-source Redis version)

Deployment Modes

• ElastiCache Serverless (launched Nov 2023)
  • zero infrastructure management with instant auto-scaling
  • pay-per-use pricing based on data stored (GB-hour) and ElastiCache Processing Units (ECPUs)
  • creates a cache in under a minute; starts as low as $6/month with Valkey
  • zero downtime maintenance
• Node-based (self-designed clusters)
  • fine-grained control over node type, count, and placement
  • supports Reserved Nodes for cost savings
  • Graviton3-based nodes available for better price-performance

Ideal Usage Patterns

• improving application performance by storing critical data in-memory for low latency access
• use cases involve usage as a database front end for read heavy applications, improving performance and reducing load on databases, or managing user session data, cache dynamically generated pages, or compute intensive calculations etc.
• Real-time search (2026) — full-text, exact-match, numeric range, and hybrid search with microsecond latency
• Vector similarity search — AI-driven semantic retrieval for RAG and recommendation systems

Anti-Patterns

• Persistent Data
  • If the application needs fast access to data coupled with strong data durability, Amazon DynamoDB would be a better option
  • Note: ElastiCache for Valkey now supports durability with Multi-AZ transactional log (June 2026), enabling fast failover and data recovery without data loss

Performance

• provides microsecond read latency and single-digit millisecond write latency with throughput up to millions of requests per second
• Valkey 9.0 (May 2026) introduces enhanced search capabilities with full-text, hybrid, and aggregation queries directly in the cache

Durability & Availability

• provides up to 99.99% availability SLA with Multi-AZ deployments
• With the Memcached engine
  • all ElastiCache nodes in a single cache cluster are provisioned in a single Availability Zone.
  • ElastiCache automatically monitors the health of your cache nodes and replaces them in the event of network partitioning, host hardware, or software failure.
  • In the event of cache node failure, the cluster remains available, but performance may be reduced due to time needed to repopulate the cache in the new “cold” cache nodes.
  • To provide enhanced fault-tolerance for Availability Zone failures or cold-cache effects, you can run redundant cache clusters in different Availability Zones.
• With the Valkey/Redis OSS engine,
  • ElastiCache supports replication to up to five read replicas for scaling. To improve availability, you can place read replicas in other Availability Zones.
  • ElastiCache monitors the primary node, and if the node becomes unavailable, ElastiCache will repair or replace the primary node if possible, using the same DNS name.
  • If the primary cache node recovery fails or its Availability Zone is unavailable, primary node can be failed over to one of the read replicas with an API call.
  • Durability support (June 2026): Multi-AZ transactional log enables data persistence across AZs, preventing data loss during failover, recovery, and node restarts.

Cost Model

• offers two pricing models:
  • Serverless: pay-per-use based on data stored (GB-hour) and ECPUs consumed. Valkey Serverless is 33% cheaper than Redis OSS Serverless.
  • Node-based: pricing per cache node-hour consumed. Supports Reserved Nodes for up to 55% savings.

Scalability & Elasticity

• ElastiCache is highly scalable and elastic.
• Serverless: instantly auto-scales to match application demand with no capacity planning
• Node-based: Cache nodes can be added or deleted from the cache cluster. Auto Discovery enables automatic discovery of Memcached cache nodes by ElastiCache Clients when the nodes are added to or removed from an ElastiCache cluster.