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Amazon ElastiCache
User Guide (API Version 2015-02-02)

Document History

The following table describes the important changes to the documentation since the last release of the Amazon ElastiCache User Guide.

  • API version: 2015-02-02

  • Latest documentation update: March 15, 2017

Change Description Date Changed
Enhanced Redis restore

ElastiCache added enhanced Redis backup and restore with cluster resizing. This feature supports restoring a backup to a cluster with a different number of shards (for the API and CLI, a different number of node groups) than the cluster used to create the backup, along with different Redis slot configurations.

For more information, see Restoring From a Backup with Cluster Resizing.

March 15, 2017
New Redis memory management parameter

ElastiCache added a new Redis parameter, reserved-memory-percent, which makes managing your reserved memory easier. This parameter is available on all versions of ElastiCache for Redis.

For more information, see Managing Reserved Memory (Redis) and New Parameters for Redis 3.2.4.

March 15, 2017
Support for Memcached 1.4.33

ElastiCache added support for Memcached version 1.4.33.

For more information, see Memcached Version 1.4.33 and Memcached 1.4.33 Added Parameters.

December 20, 2016
Support for EU West (London) Region

ElastiCache added support for EU (London) Region. Only node types T2 and M4 are currently supported.

For more information, see Supported Regions & Endpoints and Supported Node Types.

December 13, 2016

Support for Canada (Montreal) Region

ElastiCache added support for the Canada (Montreal) Region. Only node type M4 and T2 are currently supported in this region.

For more information, see Supported Regions & Endpoints and Supported Node Types.

December 8, 2016
Support for M4 and R3 node types

ElastiCache added support for R3 and M4 node types in South America (São Paulo) Region and M4 node types in China (Beijing) Region.

For more information, see Supported Regions & Endpoints and Supported Node Types.

November 1, 2016
US East 2 (Ohio) Region support

ElastiCache added support for the US East (Ohio) Region (us-east-2) with M4, T2, and R3 node types.

For more information, see Supported Regions & Endpoints and Supported Node Types.

October 17, 2016
Support for Redis Cluster

ElastiCache adds support for Redis Cluster (enhanced). Customers using Redis Cluster, can partition their data across up to 15 shards (node groups). Each shard supports replication with up to 5 read replicas per shard. Redis Cluster automatic failover times are about one fourth as long as those of earlier versions.

This release includes a redesigned management console that uses terminology in keeping with industry usage.

For more information, see the following topics:

October 12, 2016
M4 node type support

ElastiCache added support for the M4 family of node types in most regions supported by ElastiCache. You can purchase M4 node types as On-Demand or as Reserved Cache Nodes.

For more information, see Supported Node Types, Memcached Node-Type Specific Parameters, and Redis Node-Type Specific Parameters.

August 3, 2016
Mumbai Region support

ElastiCache added support for the Asia Pacific (Mumbai) Region.

For more information, see Supported Regions & Endpoints.

June 27, 2016
Snapshot export

ElastiCache added the ability to export a Redis snapshot so you can access it from outside ElastiCache.

For more information, see Exporting a Backup in the Amazon ElastiCache User Guide and CopySnapshot in the Amazon ElastiCache API Reference.

May 26, 2016
Node type scale up

ElastiCache added the ability to scale up your Redis node type.

For more information, see Scaling.

March 24, 2016
Easy engine upgrade

ElastiCache added the ability to easily upgrade your Redis cache engine.

For more information, see Upgrading Engine Versions.

March 22, 2016
Support for R3 node types

ElastiCache added support for R3 node types in the China (Beijing) and South America (Sao Paulo) regions.

For more information, see Supported Node Types.

March 16, 2016
Accessing ElastiCache using a Lambda function

Added a tutorial on configuring a Lambda function to access ElastiCache in an Amazon VPC.

For more information, see ElastiCache Tutorials.

February 12, 2016
Support for Redis 2.8.24

ElastiCache added support for Redis version 2.8.24 with improvements added since Redis 2.8.23. Improvements include bug fixes and support for logging bad memory access addresses.

For more information, see Redis Version 2.8.24 (Enhanced) and Redis 2.8 Release Notes.

January 20, 2016
Support for Asia Pacific (Seoul) Region

ElastiCache added support for the Asia Pacific (Seoul) (ap-northeast-2) Region with t2, m3, and r3 node types.

January 6, 2016

Amazon ElastiCache console change.

Because the newer Redis versions provide a better and more stable user experience, Redis versions 2.6.13, 2.8.6, and 2.8.19 are no longer listed in the ElastiCache Management Console.

For other options and more information, see Comparing Redis Versions.

December 15, 2015

Support for Redis 2.8.23.

ElastiCache added support for Redis version 2.8.23 with improvements added since Redis 2.8.22. Improvements include bug fixes and support for the new parameter close-on-slave-write which, if enabled, disconnects clients who attempt to write to a read-only replica.

For more information, see Redis Version 2.8.23 (Enhanced).

November 13, 2015

Support for Redis 2.8.22.

ElastiCache added support for Redis version 2.8.22 with ElastiCache added enhancements and improvements since version 2.8.21. Improvements include:

  • Implementation of a forkless save process that enables a successful save when low available memory could cause a forked save to fail.
  • Additional CloudWatch metrics – SaveInProgress and ReplicationBytes.
  • To enable partial synchronizations, the Redis parameter repl-backlog-size now applies to all clusters.

For a complete list of changes and more information, see Redis Version 2.8.22 (Enhanced).

This documentation release includes a reorganization of the documentation and removal of the ElastiCache command line interface (CLI) documentation. For command line use, refer to the AWS Command Line for ElastiCache.

September 28, 2015

Support for Memcached 1.4.28.

ElastiCache added support for Memcached version 1.4.24 and Memcached improvements since version 1.4.14. This release adds support for least recently used (LRU) cache management as a background task, choice of jenkins or murmur3 as your hashing algorithm, new commands, and miscellaneous bug fixes.

For more information, go to Memcached release notes and Comparing Memcached Versions in the ElastiCache User Guide.

August 27, 2015

Support for Redis 2.8.21.

Support for Memcached Auto Discovery using PHP 5.6.

ElastiCache added support for Redis version 2.8.21 and Redis improvements since version 2.8.19. This Redis release includes several bug fixes.

For more information, go to Redis 2.8 release notes.

This release of Amazon ElastiCache adds support for Memcached Auto Discovery client for PHP version 5.6.

For more information, go to Compiling the Source Code for the ElastiCache Cluster Client for PHP.

July 29, 2015

New topic: Accessing ElastiCache from outside AWS

Added new topic on how to access ElastiCache resources from outside AWS.

For more information , go to ElastiCache's Accessing ElastiCache Resources from Outside AWS.

July 9, 2015

Node replacement messages added

ElastiCache added three messages pertaining to scheduled node replacement. ElastiCache:NodeReplacementScheduled, ElastiCache:NodeReplacementRescheduled, and ElastiCache:NodeReplacementCanceled.

For more information and actions you can take when a node is scheduled for replacement, go to ElastiCache's Event Notifications and Amazon SNS.

June 11, 2015

Support for Redis v. 2.8.19.

ElastiCache added support for Redis version 2.8.19 and Redis improvements since version 2.8.6. This support includes support for:

  • The HyperLogLog data structure, with the Redis commands PFADD, PFCOUNT, and PFMERGE.
  • Lexicographic range queries with the new commands ZRANGEBYLEX, ZLEXCOUNT, and ZREMRANGEBYLEX.
  • Introduced a number of bug fixes, namely preventing a primary node from sending stale data to replica nodes by failing the master SYNC when a background save (bgsave) child process terminates unexpectedly.

For more information on HyperLogLog, go to Redis new data structure: the HyperLogLog. For more information on PFADD, PFCOUNT, and PFMERGE, go to the Redis Documentation and click HyperLogLog.

March 11, 2015

Support for cost allocation tags

ElastiCache added support for cost allocation tags.

For more information, see Monitoring Costs with Cost Allocation Tags.

February 9, 2015

Support for AWS GovCloud (US) Region

ElastiCache added support for the AWS GovCloud (US) (us-gov-west-1) Region.

January 29, 2015

Support for EU (Frankfurt) Region

ElastiCache added support for the EU (Frankfurt) (eu-central-1) Region.

January 19, 2015

Multi-AZ with auto failover support for Redis replication groups

ElastiCache added support for Multi-AZ with automatic failover from the primary node to a read replica in a Redis replication group. ElastiCache monitors the health of the replication group. If the primary fails, ElastiCache automatically promotes a replica to primary, then replaces the replica.

For more information, see Replication: Multi-AZ with Automatic Failover (Redis).

October 24, 2014

AWS CloudTrail logging of API calls supported

ElastiCache added support for using AWS CloudTrail to log all ElastiCache API calls.

For more information, see Logging Amazon ElastiCache API Calls Using AWS CloudTrail.

September 15, 2014

New instance sizes supported

ElastiCache added support for additional General Purpose (T2) instances.

For more information, see Parameters and Parameter Groups.

September 11, 2014

Flexible node placement supported for Memcached

ElastiCache added support for creating Memcached nodes across multiple Availability Zones.

For more information, see Step 2: Launch a Cluster.

July 23, 2014

New instance sizes supported

ElastiCache added support for additional General Purpose (M3) instances and Memory Optimized (R3) instances.

For more information, see Parameters and Parameter Groups.

July 1, 2014

PHP auto discovery

Added support for PHP version 5.5 auto discovery.

For more information, see Installing the ElastiCache Cluster Client for PHP.

May 13, 2014

Backup and restore for Redis clusters

In this release, ElastiCache allows customers to create snapshots of their Redis clusters, and create new clusters using these snapshots. A backup is a copy of the cluster at a specific moment in time, and consists of cluster metadata and all of the data in the Redis cache. Backups are stored in Amazon S3, and customers can restore the data from a snapshot into a new cluster at any time.

For more information, see ElastiCache Backup and Restore (Redis).

April 24, 2014

Redis 2.8.6

ElastiCache supports Redis 2.8.6, in addition to Redis 2.6.13. With Redis 2.8.6, customers can improve the resiliency and fault tolerance of read replicas, with support for partial resynchronization, and a user-defined minimum number of read replicas that must be available at all times. Redis 2.8.6 also offers full support for publish-and-subscribe, where clients can be notified of events that occur on the server.

March 13, 2014

Redis cache engine

ElastiCache offers Redis cache engine software, in addition to Memcached. Customers who currently use Redis can "seed" a new ElastiCache Redis cache cluster with their existing data from a Redis snapshot file, easing migration to a managed ElastiCache environment.

To support Redis replication capabilities, the ElastiCache API now supports replication groups. Customers can create a replication group with a primary Redis cache node, and add one or more read replica nodes that automatically stay synchronized with cache data in the primary node. Read-intensive applications can be offloaded to a read replica, reducing the load on the primary node. Read replicas can also guard against data loss in the event of a primary cache node failure.

September 3, 2013

Support for default Amazon Virtual Private Cloud (VPC)

In this release, ElastiCache is fully integrated with Amazon Virtual Private Cloud (VPC). For new customers, cache clusters are created in an Amazon VPC by default.

For more information, see Amazon Virtual Private Cloud (Amazon VPC) with ElastiCache.

January 8, 2013

PHP support for cache node auto discovery

The initial release of cache node auto discovery provided support for Java programs. In this release, ElastiCache brings cache node auto discovery support to PHP.

January 2, 2013

Support for Amazon Virtual Private Cloud (VPC)

In this release, ElastiCache clusters can be launched in Amazon Virtual Private Cloud (VPC). By default, new customers' cache clusters are created in an Amazon VPC automatically; existing customers can migrate to Amazon VPC at their own pace.

For more information, see Amazon Virtual Private Cloud (Amazon VPC) with ElastiCache.

December 20, 2012

Cache node auto discovery and new cache engine version

ElastiCache provides cache node auto discovery—the ability for client programs to automatically determine all of the cache nodes in a cluster, and to initiate and maintain connections to all of these nodes.

This release also offers a new cache engine version: Memcached version 1.4.14. This new cache engine provides enhanced slab rebalancing capability, significant performance and scalability improvements, and several bug fixes. There are several new cache parameters that can be configured.

For more information, see Parameters and Parameter Groups.

November 28, 2012

New cache node types

This release provides four additional cache node types.

November 13, 2012

Reserved cache nodes

This release adds support for reserved cache nodes.

April 5, 2012

New guide

This is the first release of Amazon ElastiCache User Guide.

August 22, 2011