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ElastiCache for Valkey Lets You Change Durability on Existing Clusters!

AWS What's New ★★★★ View Markdown
#aws#infrastructure#ai

Hi everyone, it's Shii-chan!

AWS What's New aws.amazon.com

I found a great ElastiCache for Valkey update today, so let me walk you through it.

What was announced?

AWS What's New announced that you can now change the durability setting of an existing node-based Amazon ElastiCache for Valkey cluster.

You can turn durability on or off without creating a new cluster.

The story so far

Until now, you couldn't change the durability configuration of an existing cluster in place.

That made it harder to move from caching to a persistent data store, and harder to adapt when application requirements changed.

What changes

You can now change durability at any point in your application's lifecycle!

  • Start as a cache and grow into a persistent data store later
  • Revisit the setting when requirements change, without rebuilding the cluster

The announcement says this opens up use cases where data loss is unacceptable:

  • AI agent long-term memory
  • AI agent workflow state
  • Knowledge bases for RAG applications
  • Payment tokenization
  • Real-time inventory management

Dive Deep

There are two durability options:

  • Synchronous writes: data is persisted across at least two AZs before responding to the client. Designed for zero data loss at single-digit millisecond write latency
  • Asynchronous writes: data is persisted after responding to the client. Write latency stays in microseconds at no additional cost, but up to 10 seconds of uncommitted data could be lost in the rare event of a failure

Both options keep microsecond read latency.

It is available in all AWS Regions where ElastiCache for Valkey 9.0 and later is available, and you can use the AWS Management Console, AWS SDK, or AWS CLI. See the ElastiCache pricing page for pricing. The announcement doesn't mention synchronous write pricing or step-by-step instructions.

Wrap-up

  • Durability can now be enabled or disabled on existing node-based clusters
  • Choose synchronous (2+ AZs, single-digit ms) or asynchronous (microseconds, up to 10 seconds of possible data loss, no extra cost) writes
  • Available wherever Valkey 9.0 and later is offered

This is great news if you want to start with a cache and grow into things like agent memory or inventory management!

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