A company needs to extend its storage infrastructure to the AWS Cloud. The storage needs to be available as iSCSI devices for on-premises application servers. What should be done to fulfill this requirement?

Answer options:

A.Create a Glacier vault. Use a Glacier Connector and mount it as an iSCSI device.
B.Create an S3 bucket. Use an S3 Connector and mount it as an iSCSI device.
C.Use the EFS file service and mount the different file systems to the on-premises servers.
D.Use the AWS Storage Gateway-cached volumes service.

Correct Answer - D
AWS Documentation mentions the following:
By using cached volumes, you can use Amazon S3 as your primary data storage, while retaining frequently accessed data locally in your storage gateway. Cached volumes minimize the need to scale your on-premises storage infrastructure while still providing your applications with low-latency access to their frequently accessed data. You can create storage volumes up to 32 TB in size and attach iSCSI devices to them from your on-premises application servers. Your gateway stores data that you write to these volumes in Amazon S3, retains recently read data in your on-premises storage gateway`s cache, and upload buffer storage.
Options A, B and C are incorrect because they cannot be mounted as iSCSI devices to the on-premises application servers.
Option D is CORRECT because AWS Storage Gateway connects an on-premises software appliance with cloud-based storage to provide seamless integration with data security features between your on-premises IT environment and the AWS storage infrastructure. The storage can also be mounted as iSCSI devices to the on-premises application servers.
For more information on AWS Storage Gateways, please visit the following URL:
https://docs.aws.amazon.com/storagegateway/latest/userguide/StorageGatewayConcepts.html