Error: elasticache oom command not allowed when used memory maxmemory

Solution

Detailed Solution for "ElastiCache OOM Command Not Allowed When Used Memory MaxMemory" Error

1. Understand the Cause

• The error occurs when the Redis instance reaches its maximum configured memory limit.
• The "OOM" in the error stands for Out Of Memory, indicating that there isn't enough available memory to execute the requested command.

2. Increase the 'maxmemory' Setting

• You can increase the 'maxmemory' setting within the ElastiCache console or through the AWS CLI.
• This will allow Redis to use more memory, but it may increase your costs.

3. Modify the 'maxmemory-policy'

• By default, the 'maxmemory-policy' is set to 'volatile-lru', which removes the least recently used keys first, but only among keys that have an expiration set.
• If most of your keys do not have an expiration set, changing the policy to 'allkeys-lru' might prevent the OOM errors.
• This policy considers all keys for removal, not just those with an expiration.

4. Review Application Logic

• Review your application logic to ensure proper handling of data storage and retrieval.
• Implement strategies like caching less frequently used data, setting appropriate TTLs (Time To Live), or even partitioning your data across multiple Redis instances if high memory usage persists.

5. Monitor Memory Usage

• Regularly monitor the memory usage of your Redis instance to identify potential issues before they cause OOM errors.
• Use tools like Redis INFO command or monitoring tools provided by AWS to track memory usage.

6. Seek Additional Help

• If none of the above solutions resolve the issue, seek help from the AWS support team or Redis community forums.
• Provide detailed information about your Redis configuration, the steps you've already tried, and any error messages you encounter.

By following these steps, you should be able to identify and resolve the "ElastiCache OOM command not allowed when used memory maxmemory" error. Remember to regularly monitor your Redis instance's memory usage to prevent future issues.