A company uses Amazon OpenSearch Service to analyze data. It loads data into an OpenSearch cluster with 10 data nodes from an S3 bucket that uses S3 Standard. The data remains in the cluster for one month for read-only analysis, after which the index is deleted. For compliance, the company must retain a copy of all input data. The company wants to reduce ongoing costs. Which solution meets the requirements most cost-effectively?

The correct solution leverages UltraWarm storage for cost-effective analysis and S3 Glacier Deep Archive for long-term, compliant data retention. UltraWarm nodes in OpenSearch Service are designed for read-only data that is accessed less frequently, offering significantly lower costs than hot data nodes while still providing interactive query performance. Reducing the number of hot data nodes to 2 minimizes the cost of frequently accessed storage. Transitioning input data to S3 Glacier Deep Archive after one month provides the most cost-effective long-term storage for compliance, as it has the lowest storage cost among S3 storage classes. Incorrect options: Replacing all data nodes with UltraWarm nodes might not provide sufficient performance for initial ingestion and active analysis, and transitioning S3 files immediately to Glacier Deep Archive would incur retrieval costs if the data were needed from S3 within the month. Adding cold storage nodes is unnecessary as UltraWarm nodes are sufficient for the read-only analysis, and deleting input data from S3 after one month violates the compliance requirement for retaining a copy. Instance-backed data nodes are standard hot nodes and do not offer the cost savings of UltraWarm for read-only data, making this option less cost-effective.