Answer: Move the catalog to an Amazon Elastic File System (Amazon EFS) file system.

## Explanation **Why D is correct:** 1. **Instance Store Limitations:** EC2 instance stores are ephemeral storage that is physically attached to the host computer. Data on instance stores is lost when: - The instance is stopped or terminated - The underlying host fails - The instance is hibernated 2. **Amazon EFS Benefits:** - **High Availability:** EFS is a fully managed, highly available file storage service that automatically replicates data across multiple Availability Zones within a region. - **Durability:** EFS is designed for 99.999999999% (11 nines) durability. - **Shared Access:** Multiple EC2 instances can access the same EFS file system simultaneously, making it ideal for shared catalogs. - **Managed Service:** AWS handles the underlying infrastructure, scaling, and maintenance. **Why other options are incorrect:** - **A. Amazon ElastiCache for Redis:** This is an in-memory data store, not suitable for persistent storage of a catalog. Data in ElastiCache is volatile and can be lost if nodes fail. - **B. Deploy a larger EC2 instance with a larger instance store:** This doesn't solve the fundamental problem. Instance stores are still ephemeral and not highly available across multiple instances. - **C. Amazon S3 Glacier Deep Archive:** This is designed for long-term archival storage with retrieval times of 12+ hours, not for active website catalogs that need immediate access. **Key AWS Concepts:** - **Instance Store:** Ephemeral block-level storage physically attached to the host computer - **Amazon EFS:** Fully managed, highly available, shared file storage service - **High Availability:** Ability of a system to remain operational for a long period - **Durability:** Long-term data protection and preservation **Best Practice:** For shared, highly available, and durable storage that needs to be accessed by multiple EC2 instances, Amazon EFS is the appropriate AWS service.

Author: LeetQuiz Editorial Team