This page describes how your Memorystore instance behaves during a version upgrade operation, how an upgrade operation can affect your application, and when you should run an upgrade operation. To learn how to upgrade an instance's Redis version, see Upgrading an instance's Redis version.
Depending on the instance's tier, running a version upgrade operation can have performance and storage implications for your application. There are also some limitations to upgrading instances based on the amount of memory that is currently in use.
Best practices for upgrading an instance's Redis version
We recommend exporting your instance data before running a version upgrade operation.
For Standard Tier instances, to increase the speed and reliability of your version upgrade operation, upgrade your instance during periods of low instance traffic. To learn how to monitor instance traffic, see Monitoring Redis instances.
When upgrading a Standard Tier instance, keep the instance write load to a minimum. A high write load can cause upgrade operations to take significantly longer, and can cause upgrades to fail.
Version upgrade behavior
Data is preserved during a version upgrade operation for both Basic and Standard Tier instances. During an upgrade operation the instance undergoes a short connection reset of a couple minutes, or less. Applications should incorporate retry logic in the code to be able to reconnect to the instance. The IP address and connection string remain the same.
Because of the short term connection break, there may be a small amount of stale or inconsistent data that didn't write or update to the cache for the short amount of time the instance was unavailable.
Write load during an upgrade
You should upgrade an instance during a period of low instance traffic to minimize the performance impact on your application. A high write load, or high memory pressure, can cause an upgrade operation to take significantly longer and can cause the upgrade to fail. For more information see Scaling and version upgrade operations.
When you upgrade a Standard Tier instance, expired keys are not synced. If you have expired keys in your Redis instance before you upgrade, you will have fewer keys after the instance is upgraded.