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

Supported ElastiCache for Redis Versions

If you enable at-rest encryption, in-transit encryption, and Redis AUTH when you create a Redis cluster using ElastiCache for Redis version 3.2.6 or 4.0.10, you can use Amazon ElastiCache for Redis to build HIPAA-compliant applications. You can store healthcare-related information, including protected health information (PHI), under an executed Business Associate Agreement (BAA) with AWS. AWS Services in Scope have been fully assessed by a third-party auditor and result in a certification, attestation of compliance, or Authority to Operate (ATO). For more information, see the following topics:

Note

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 deprecated when using the ElastiCache console. We recommend against using these Redis versions. If you need to use one of them, work with the AWS CLI or ElastiCache API.

For more information, see the following topics:

AWS CLI ElastiCache API

Create Cluster

Creating a Cluster (AWS CLI)

This action cannot be used to create a replication group with cluster mode enabled.

Creating a Cluster (ElastiCache API)

This action cannot be used to create a replication group with cluster mode enabled.

Modify Cluster

Using the AWS CLI

This action cannot be used to create a replication group with cluster mode enabled.

Using the ElastiCache API

This action cannot be used to create a replication group with cluster mode enabled.

Create Replication Group

Creating a Redis (cluster mode disabled) Replication Group from Scratch (AWS CLI)

Creating a Redis (cluster mode enabled) Replication Group from Scratch (AWS CLI)

Creating a Redis (cluster mode disabled) Replication Group from Scratch (ElastiCache API)

Creating a Redis (cluster mode enabled) Replication Group from Scratch (ElastiCache API)

Modify Replication Group

Modifying a Replication Group (AWS CLI)

This action cannot be used to modify a replication group with cluster mode enabled.

Modifying a Replication Group (ElastiCache API)

This action cannot be used to modify a replication group with cluster mode enabled.

ElastiCache for Redis Version 4.0.10 (Enhanced)

Amazon ElastiCache for Redis introduces the next major version of the Redis engine supported by Amazon ElastiCache. ElastiCache for Redis 4.0.10 brings support the following improvements:

Redis (cluster mode disabled) users running Redis version 3.2.10 can use the console to upgrade their clusters via online upgrade.

Comparing ElastiCache for Redis Cluster Resizing and Encryption Support

Version
Feature 3.2.6 3.2.10 4.0.10
Online cluster resizing * No Yes Yes
In-transit encryption ** Yes No Yes
At rest encryption Yes No Yes
* Adding, removing, and rebalancing shards.
** Required for HIPAA compliant applications.

ElastiCache for Redis Version 3.2.10 (Enhanced)

Amazon ElastiCache for Redis introduces the next major version of the Redis engine supported by Amazon ElastiCache. ElastiCache for Redis 3.2.10 introduces online cluster resizing to add or remove shards from the cluster while it continues to serve incoming I/O requests. ElastiCache for Redis 3.2.10 users have all the functionality of earlier Redis versions except the ability to encrypt their data which is currently only available in version 3.2.6.

Comparing ElastiCache for Redis versions 3.2.6 and 3.2.10

Version
Feature 3.2.6 3.2.10
Online cluster resizing * No Yes
In-transit encryption ** Yes No
At rest encryption Yes No
* Adding, removing, and rebalancing shards.
** Required for HIPAA compliant applications.

For more information, see:

ElastiCache for Redis Version 3.2.6 (Enhanced)

Amazon ElastiCache for Redis introduces the next major version of the Redis engine supported by Amazon ElastiCache. ElastiCache for Redis 3.2.6 users have all the functionality of earlier Redis versions plus the option to encrypt their data. For more information, see:

ElastiCache for Redis Version 3.2.4 (Enhanced)

Amazon ElastiCache for Redis version 3.2.4 introduces the next major version of the Redis engine supported by Amazon ElastiCache. ElastiCache for Redis 3.2.4 users have all the functionality of earlier Redis versions available to them plus the option to run in cluster mode or non-cluster mode. The following table summarizes .

Comparing Redis 3.2.4 Non-Cluster Mode and Cluster Mode

Feature Non-Cluster Mode Cluster Mode
Data partitioning No Yes
Geospatial indexing Yes Yes
Change node type Yes Yes *
Replica scaling Yes Yes *
Scale out No Yes *
Database support Multiple Single

Parameter group

default.redis3.2 **

default.redis3.2.cluster.on **

*  See Restoring From a Backup with Optional Cluster Resizing

** Or one derived from it.

Notes:

  • Partitioning – the ability to split your data across 2 to 15 node groups (shards) with replication support for each node group.

  • Geospatial indexing – Redis 3.2.4 introduces support for geospatial indexing via six GEO commands. For more information, see the Redis GEO* command documentation Redis Commands: GEO on the Redis Commands page (filtered for GEO).

For information about additional Redis 3 features, see Redis 3.2 release notes and Redis 3.0 release notes.

Currently ElastiCache managed Redis (cluster mode enabled) does not support the following Redis 3.2 features:

  • Replica migration

  • Cluster rebalancing

  • Lua debugger

ElastiCache disables the following Redis 3.2 management commands:

  • cluster meet

  • cluster replicate

  • cluster flushslots

  • cluster addslots

  • cluster delslots

  • cluster setslot

  • cluster saveconfig

  • cluster forget

  • cluster failover

  • cluster bumpepoch

  • cluster set-config-epoch

  • cluster reset

For information about Redis 3.2.4 parameters, see Redis 3.2.4 Parameter Changes.

ElastiCache for Redis Version 2.8.24 (Enhanced)

Redis improvements added since version 2.8.23 include bug fixes and logging of bad memory access addresses. For more information, see Redis 2.8 release notes.

ElastiCache for Redis Version 2.8.23 (Enhanced)

Redis improvements added since version 2.8.22 include bug fixes. For more information, see Redis 2.8 release notes. This release also includes 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 on Redis 2.8.23 parameters, see Redis 2.8.23 (Enhanced) Added Parameters in the ElastiCache User Guide.

ElastiCache for Redis Version 2.8.22 (Enhanced)

Redis improvements added since version 2.8.21 include the following:

  • Support for forkless backups and synchronizations, which allows you to allocate less memory for backup overhead and more for your application. For more information, see How Synchronization and Backup are Implemented. The forkless process can impact both latency and throughput. In the case of high write throughput, when a replica re-syncs, it may be unreachable for the entire time it is syncing.

  • In the event of a failover, replication groups now recover faster because replicas perform partial syncs with the primary rather than full syncs whenever possible. Additionally, both the primary and replicas no longer use the disk during syncs, providing further speed gains.

  • Support for two new CloudWatch metrics.

    • ReplicationBytes – The number of bytes a replication group's primary cluster is sending to the read replicas.

    • SaveInProgress – A binary value that indicates whether or not there is a background save process running.

    For more information, see Monitoring Use with CloudWatch Metrics.

  • A number of critical bug fixes in replication PSYNC behavior. For more information, see Redis 2.8 release notes.

  • To maintain enhanced replication performance in Multi-AZ replication groups and for increased cluster stability, non-ElastiCache replicas are no longer supported.

  • To improve data consistency between the primary cluster and replicas in a replication group, the replicas no longer evict keys independent of the primary cluster.

  • Redis configuration variables appendonly and appendfsync are not supported on Redis version 2.8.22 and later.

  • In low-memory situations, clients with a large output buffer may be disconnected from a replica cluster. If disconnected, the client needs to reconnect. Such situations are most likely to occur for PUBSUB clients.

ElastiCache for Redis Version 2.8.21

Redis improvements added since version 2.8.19 include a number of bug fixes. For more information, see Redis 2.8 release notes.

ElastiCache for Redis Version 2.8.19

Redis improvements added since version 2.8.6 include the following:

  • Support for HyperLogLog. For more information, see Redis new data structure: HyperLogLog.

  • The sorted set data type now has support for lexicographic range queries with the new commands ZRANGEBYLEX, ZLEXCOUNT, and ZREMRANGEBYLEX.

  • To prevent a primary node from sending stale data to replica nodes, the master SYNC fails if a background save (bgsave) child process is aborted.

  • Support for the HyperLogLogBasedCommands CloudWatch metric. For more information, see Metrics for Redis.

ElastiCache for Redis Version 2.8.6

Redis improvements added since version 2.6.13 include the following:

  • Improved resiliency and fault tolerance for read replicas.

  • Support for partial resynchronization.

  • Support for user-defined minimum number of read replicas that must be available at all times.

  • Full support for pub/sub—notifying clients of events on the server.

  • Automatic detection of a primary node failure and failover of your primary node to a secondary node.

ElastiCache for Redis Version 2.6.13

Redis version 2.6.13 was the initial version of Redis supported by Amazon ElastiCache for Redis. Multi-AZ with automatic failover is not supported on Redis 2.6.13.