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

Self-Service Updates in Amazon ElastiCache

Amazon ElastiCache automatically monitors your fleet of Redis clusters and nodes to apply service updates as they become available. This typically means that you must set up a pre-defined maintenance window so that ElastiCache can apply these updates, which you might find too rigid and might constrain your business flows. With self-service updates, you control when and which updates are applied. You can also monitor the progress of these updates to your selected Redis clusters in real-time. Depending on your business requirements, you can choose to stop the update to remaining nodes and clusters. You can select a new set of clusters (including the ones that were partially updated) to apply the service updates anytime until the service update expires.