Understanding DMS replication instance endpoint limit

Your understanding of AWS DMS replication instance limits requires some clarification. While it's true that there are limits on both tasks and endpoints per replication instance, these limits work independently and the actual number of tasks you can run depends on several factors.

First, it's important to note that the limit of endpoints per replication instance is indeed 100. However, this doesn't necessarily mean you're limited to 50 tasks per instance. The key point here is that endpoints can be reused across multiple tasks.

If you have multiple tasks that use the same source or target endpoint, that endpoint only counts once towards the 100-endpoint limit. This means you can potentially run more tasks than you might initially think.

In your specific scenario, where 100 source endpoints target the same target endpoint, you could theoretically run up to 99 DMS tasks on a single instance, assuming you're within other resource limits. The single target endpoint and the 99 source endpoints would count towards your 100-endpoint limit.

However, it's crucial to remember that the number of tasks you can effectively run on a replication instance also depends on other factors such as:

1. The size and resources of your replication instance
2. The complexity and data volume of your migration tasks
3. The performance requirements of your migration

While you might be able to configure 99 tasks on a single instance in your scenario, you need to ensure that the instance has sufficient CPU, memory, and storage to handle the workload of all these tasks efficiently.

For optimal performance, it's recommended to monitor your replication instance's resource utilization closely using Amazon CloudWatch metrics like CPUUtilization, FreeableMemory, and SwapUsage. If you're pushing the limits of your instance, you might need to consider using a larger instance type or distributing your tasks across multiple replication instances.

Remember, AWS DMS is designed to be flexible, allowing you to balance your workload across resources as needed for your specific migration scenario. Always consider your specific requirements and monitor performance to ensure efficient data migration.
Sources
Tune replication performance with AWS DMS for an Amazon Kinesis Data Streams target endpoint – Part 1 | AWS Database Blog
Components of AWS DMS - AWS Database Migration Service
2: AWS DMS replication instance: Create - AMS Advanced Application Developer's Guide