The new mobile application that you are building will accept images and videos from the mobile app and will store, enhance, watermark, and deliver them to other users. As per the initial research, it seems that EFS will be a suitable option as the application will be running behind a load balancer. The file system will be shared among the instances so that the data can be delivered fast. Your company has decided to use the CloudFront before the load balancer to geocache the contents and serve it faster. Which of the following statements of EFS are correct when working with the application? (Select TWO.)

Answer options:

A.EFS is not highly-available and will require periodic backup to ensure no data is at a loss.
B.The throughput of EFS increases with storage capacity, so the download is always faster with more data.
C.The EFS is mounted in the local file system of EC2 instances and your application needs to handle all the upload/download processing.
D.Encryption in transit and at the storage level is not available. So in the future, if your application needs encryption, EFS will not be the right choice.
E.EFS performance is dependent on storage size. Under heavy load such as when the throughput limit exceeds 1024 MiB/s, EFS may start to throttle unexpectedly.

Correct Answer: C, E
Option A is INCORRECT because Amazon EFS data is distributed across multiple Availability Zones (AZs), providing a high durability and availability level.
Option B is INCORRECT because EFS supports two throughput modes to choose from for your file system, Bursting Throughput, and Provisioned Throughput. With Bursting Throughput mode, throughput on Amazon EFS scales as your file system grows. File-based workloads are typically spiky, driving high levels of throughput for short periods of time and low levels of throughput the rest of the time. To accommodate this, EFS is designed to burst to high throughput levels for periods of time.
Option C is CORRECT because EFS serves as a local file system and is not directly accessible. All the read/write operations have to be done via the EC2 with which it is attached.
Option D is INCORRECT because EFS provides both in-transit and at-rest encryption options using the AWS KMS service.
Option E is CORRECT because EFS uses a credit system to determine when file systems can burst. Each file system earns credits over time at a baseline rate determined by the size of the file system and uses credits whenever it reads or writes data. So if you have proportionally high read/write compared to overall data, you may face the burst capacity issues and opt to the Throughput Provisioned Mode.
Specifying Throughput with Provisioned Mode
AWS EFS supports Provisioned Throughput mode, which allows applications configured to provision the throughput irrespective of the data stored inside the file system. This means applications with higher throughput requirements can use this mode to achieve higher performance.
Keep in mind that Provisioned Throughput is billed separately from the data storage depending on the capacity.