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What Is ElastiCache? An Essential Guide to Cloud Caching

Originally Published January, 2024 · Last Updated July, 2024

ElastiCache improves your application’s performance by retrieving data from fast, managed, in-memory systems instead of relying on slower disk-based databases. It’s the perfect solution for gaming, e-commerce, healthcare, the Internet of Things, and other latency-sensitive use cases for AWS Cloud that need real-time data access.

But, with monthly pricing expenses ranging from $20-25 USD on the lower end to up to $1,000 USD a month for large-scale deployments, smart AWS cost management is key to optimizing your ElastiCache usage for the best ROI.

Let’s talk about what you need to know about the platform to make the most efficient use of its resources without burning a hole through your company’s IT budget.

What is Amazon ElastiCache?

Amazon ElastiCache is a fully managed in-memory data store and cache service that improves application performance by allowing you to retrieve information from fast, managed, memory-based caching systems instead of relying entirely on slower disk-based databases.

It supports two popular open-source in-memory engines: Memcached and Redis. Memcached is a simple key-value caching system, while Redis supports more complex data structures like lists, sets, sorted sets, and hashes in addition to key-value.

ElastiCache sits between your applications and databases to help ease the load off your databases by caching frequently accessed or compute-intensive data. This improves read speeds, throughput, and overall application performance.

Some key capabilities and benefits of Amazon ElastiCache include:

  • Serverless deployment: ElastiCache can instantly deploy and scale Redis caches without capacity planning. It auto-scales to meet application demands.
  • High availability: Multi-AZ deployments with auto-failover provide high availability with 99.99% SLA.
  • Security: Encryption at rest and in transit, VPC support, IAM policies, and AWS compliance.
  • Integration: Works seamlessly with various AWS services like Amazon RDS, EKS, Lambda, CloudTrail, and S3.
  • Backup and restore: Point-in-time recovery, backup, and restore features.
  • Monitoring and automation: CloudWatch, events, logs, and API/SDK access for automation.

Benefits of using ElastiCache

Amazon ElastiCache is a caching service with significant performance, scalability, integration, availability, and reliability benefits. By adding a managed in-memory data layer, ElastiCache enhances application speed and throughput—plus several other benefits we’ll explore below.

Better application performance

AWS ElastiCache dramatically boosts application performance by reducing latency and accelerating read speeds. It achieves this by caching frequently accessed or compute-intensive data into ultra-fast in-memory systems instead of relying solely on slower disk-based databases.

Retrieving data from RAM is orders of magnitude faster than disk I/O. Reading 1 MB sequentially from memory takes about 250 microseconds, while reading from SSD takes 1,000 times longer at 250 milliseconds. This difference is even more pronounced for random reads. ElastiCache leverages all of this for a huge speed advantage.

By serving cached data from low-latency in-memory stores like Redis and Memcached rather than hitting disk-bound databases for every query, applications see dramatic improvements in response times and throughput. Pages load faster, queries return quicker, and the overall user experience is smoother.

Moreover, ElastiCache also helps minimize database load. By offloading non-transactional queries to cached data, ElastiCache applications apply less strain to databases. This further improves system performance and scalability.


One of the major benefits of Amazon ElastiCache is its ability to scale seamlessly— both vertically and horizontally—to meet growing application demands.

ElastiCache enables automatic vertical scaling by allowing you to resize cache nodes to larger instance types with a single click. Going from a cache.r5.large to cache.r5.xlarge, for example, provides more CPU, memory, and network resources for improved performance.

More importantly, ElastiCache delivers effortless horizontal scaling through sharding and read replicas. Sharding automatically partitions your dataset across multiple nodes as it grows. Read replicas offload read traffic, further increasing throughput.

ElastiCache will automatically detect increased load and scale out your cluster by adding shards or read replicas. This maintains steady performance during traffic spikes and data surges. You can also provision additional nodes in minutes with no downtime, all handled automatically by the service.

Similarly, when there’s a decrease in demand, ElastiCache will scale resources back in to optimize costs. This eliminates the need to manually tune capacity and enables apps to sustain peak efficiency as workloads shift.

Easy integration

A key benefit of ElastiCache is its seamless integration into AWS-based applications and services. This makes it fast and easy to enhance the performance of existing systems with a managed in-memory cache.

ElastiCache works out of the box with popular AWS compute, database services, analytics, and monitoring services. For example, you can set up ElastiCache to cache data from RDS databases like Amazon Aurora, offloading read traffic to improve performance and reduce database load.

Integration with AWS SDKs and tooling streamlines management as well. You can monitor usage metrics through Amazon CloudWatch while events and logs enable automation around scaling, security, availability, and more.

ElastiCache for Redis also offers enhanced integration features like clustering with Amazon EKS for simplified deployments on Kubernetes and integration with AWS Lambda to trigger functions based on cache events.

You can easily embed ElastiCache directly into most AWS application architectures to start reaping the benefits of high-speed caching and in-memory data storage. Seamless integration minimizes complexity for developers deploying or migrating apps to AWS.

High availability and reliability

Amazon ElastiCache offers robust high availability and reliability features to ensure critical applications can withstand failures and deliver consistent performance. Together, these mechanisms allow ElastiCache to guarantee 99.99% uptime even for mission-critical workloads.

A key capability is Multi-AZ deployments with automatic failover. ElastiCache provisions primary and standby nodes across Availability Zones, continuously replicating data between them. If the primary node fails for any reason, ElastiCache will automatically promote the standby to take its place with typically under 60-120 seconds of downtime.

ElastiCache also provides resilience against zone or region-level disasters via cross-region replication. You can have a replica cluster in another region continuously synced from your primary cluster. You can even promote this replica to become the new primary in the event of a large-scale failure.

Finally, the service delivers high reliability through continuous monitoring and self-healing capabilities. It automatically restarts, recovers, and replaces unhealthy nodes to maintain maximum uptime.

How does ElastiCache work?

With Amazon ElastiCache, AWS provides a fully managed caching service that provides sub-millisecond data access speeds to improve application performance. Under the hood, ElastiCache handles provisioning, scaling, patching, failure handling, and more to run Memcached or Redis protocol-compliant cache clusters.

Here’s how everything comes together:

1. Data storage

ElastiCache stores data in managed in-memory systems for microsecond access times instead of slower disk-based databases. Redis offers more advanced data types like lists, hashes, sets, sorted sets, and HyperLogLog, while Memcached focuses on high-performance key-value caching.

Both engines keep hot datasets in memory for sub-millisecond reads. Redis also persists data to SSD for durability. By caching frequently accessed data in RAM, applications can reduce high-latency database calls.

2. Caching algorithm

ElastiCache uses caching algorithms like Least Recently Used (LRU) to ensure hot data stays in memory while evicting cold data if it reaches capacity. This maximizes the cache hit rate.

Lazy loading populates the cache only when the system requests data, while write-through writes data to both the cache and database synchronously. Different strategies balance performance vs consistency.

These algorithms and data flows optimize cache efficiency to reduce database load and accelerate read performance.

3. Data access

When retrieving data, applications check the ElastiCache cluster first. Ultrafast memory serves the cache hits. Cache misses fetch data from the database to populate the cache for the next time before returning data to the application.

This alleviates pressure on databases while accelerating performance for end users by serving more reads from low-latency RAM.

4. Scaling and replication

ElastiCache enables effortless horizontal scaling by adding read replicas or sharding data across more nodes to handle growing loads. Vertical scaling upgrades to larger node types.

Redis supports multi-AZ for high availability. With synchronization across nodes, failure triggers automatic failover. Redis replication and sharding prevent data loss and improve read scalability.

ElastiCache scales cluster resources up and out automatically to ensure capacity meets demands.

5. Monitoring and management

ElastiCache simplifies caching infrastructure via integrated monitoring (CloudWatch), log delivery, security capabilities, automated node replacement after failures, and daily Redis backups.

These capabilities reduce management overhead while improving oversight of performance, availability, and operational health.

What is ElastiCache used for?

Amazon ElastiCache is a versatile caching service that accelerates application performance in a variety of use cases, including:

Website and application caching

ElastiCache dramatically improves website and application performance by caching frequently accessed data like popular content, recommendations, search results, and more. ElastiCache retrieves this data from managed in-memory stores instead of slower databases. Page load times drop from seconds to milliseconds while infrastructure costs decrease.

Session caching

ElastiCache provides a fast storage engine for user session data, which is accessed frequently. By enabling session data to be stored in a centralized, durable, rapid cache instead of the application server, ElastiCache maintains smooth user experiences amid traffic spikes and prevents session data loss between servers.

Database query caching

Applications can configure ElastiCache to cache the results of common queries or compute-intensive workloads, avoiding repetitive requests to databases. Reading computed values from the cache significantly accelerates performance for read-intensive applications by reducing high-latency disk I/O.

Real-time analytics and leaderboards

For real-time analytics requiring instant data ingestion and display, ElastiCache facilitates rapid number-crunching and presentation. Similarly, by tracking scores/rankings in memory, ElastiCache delivers smooth, real-time leaderboard updates and notifications.

Messaging queues

ElastiCache manages transient messaging queues to ensure reliable asynchronous communication between decoupled application components like microservices. Queue-based message processing prevents the loss of messages across components.

Geospatial data storage

ElastiCache provides a performant in-memory data store for location-based application data like coordinates, boundaries, and geospatial queries. This enables rapid processing for real-time location services, geo-fencing, and personalized user experiences.

Leverage ProsperOps for smarter AWS cost management

Managing your ElastiCache costs can be challenging, given shifting workloads and the complexity of optimizing reserved capacity. ProsperOps, a founding member of the FinOps Foundation, offers purpose-built Automated Discount Management for ElastiCache to seamlessly maximize savings on ElastiCache Reserved Nodes while balancing commitment risks. 

By automatically adjusting reserved node purchases based on real-time usage, ProsperOps provides hands-free optimization that reduces ElastiCache spend without headaches or overhead.

Sign up for a demo to learn how ProsperOps can make your Amazon Web Services infrastructure more cost-effective.



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