Collections with unique AWS KMS keys can't share OCUs with other collections.
Managing capacity limits
Although capacity can scale up to accomodate data, it can't currently scale up search replicas. OpenSearch Serverless functions with two search replicas running in active-active mode. If you need more replicas for your workload, contact AWS Support.
At this time, capacity settings only apply at the account level. You can't configure per-collection capacity limits.
Ingesting data into collections
You must have version 2.30.0 or later of the AWS for Fluent Bit image in order to integrate with OpenSearch Serverless.