Which AWS service is best for cost-effective long-term storage of infrequently accessed data?

Amazon S3 Glacier is designed specifically for cost-effective long-term storage of infrequently accessed data. It offers a storage solution that is ideal for archival storage, where data does not need to be frequently retrieved, making it significantly cheaper than standard storage options. S3 Glacier allows users to store large amounts of data at a lower cost, which is particularly beneficial for organizations that need to retain data for compliance, regulatory, or backup purposes but do not require immediate access.

The service also provides varying retrieval options that allow users to choose how quickly they need their data back, which can further optimize costs based on access needs. This tiered approach makes S3 Glacier the preferred choice for long-term data storage when compared to other options, as it strikes a balance between affordability and the specific access requirements of archival data.

In contrast, the other options serve very different purposes. For example, while Amazon Elastic File System (EFS) offers scalable file storage for applications that require low-latency access, it is not optimized for long-term archival storage. Amazon EC2 provides compute capacity but does not facilitate long-term storage; rather, it is designed to run applications. Amazon RDS is used for relational database services and is thus focused on operational data rather than inf