Q45 — AWS SAA-C03 Ch.16

Question 45 of 100 | ← Chapter 16

Q1245. A solutions architect is provisioning an Amazon Elastic File System (Amazon EFS) file system to provide shared storage across multiple Amazon EC2 instances.The instances all exist in the same VPC across multiple Availability Zones.There are two instances in each Availability Zone.The solutions architect must make the file system accessible to each instance with the lowest possible latencyWhich solution will meet these requirements?

Correct Answer: D. Create a mount target in each Availability Zone of the VPC. Use the mount target to mount the EFS file system on the instances in the respective Availability Zone.

Explanation

The solutions architect needs to provision an Amazon EFS file system that is shared across multiple EC2 instances in the same VPC but different Availability Zones (AZs) with the lowest possible latency.Key Requirements:Shared storage EFS must be accessible from all EC2 instances. Low latency Mount targets should be optimally placed to minimize cross-AZ latency. Multiple AZs Instances are in different AZs (2 instances per AZ).How Amazon EFS Works:EFS is a regional, scalable, and highly available file system. Mount targets are network endpoints (ENIs) that EC2 instances use to access the EFS file system. Best practice: Place one mount target per AZ to ensure low-latency access from instances in that AZ. Cross-AZ access is possible but introduces higher latency (data must travel between AZs).Analysis of Options:A. Create a mount target for the EFS file system in the VPC. Use the mount target to mount the file system on each of the instances.Incorrect:This implies only one mount target (likely in a single AZ). Instances in other AZs will experience higher latency when accessing the file system.Not optimal for low-latency requirements.B. Create a mount target for the EFS file system in one Availability Zone of the VPC. Use the mount target to mount the file system on the instances in that Availability Zone. Share the directory with the other instances.Incorrect:Sharing the directory (e.g., via NFS export) does not reduce latency for instances in other AZs. Instances in other AZs will still access the file system via the single mount target, leading to higher latency.Not recommended for performance-sensitive workloads.C. Create a mount target for each instance. Use each mount target to mount the EFS file system on each respective instance.Incorrect:EFS does not support per-instance mount targets.Mount targets are AZ-scoped, not instance-scoped.This option is technically impossible.D. Create a mount target in each Availability Zone of the VPC. Use the mount target to mount the EFS file system on the instances in the respective Availability Zone.Correct:Best practice for EFS performance.One mount target per AZ ensures low-latency access for instances in that AZ. Highly available (if an AZ fails, instances in other AZs can still access EFS via their local mount targets). Scalable (EFS automatically handles cross-AZ replication).Final Answer:D. Create a mount target in each Availability Zone of the VPC. Use the mount target to mount the EFS file system on the instances in the respective Availability Zone.Why This is the Best Choice:Lowest Latency: Instances access EFS via a local mount target in their own AZ. High Availability: If one AZ fails, instances in other AZs remain unaffected. Scalability: EFS automatically handles traffic distribution across mount targets. Compliance with EFS Best Practices: AWS recommends one mount target per AZ for optimal performance.Additional Notes:EFS Access Points (optional) can be used to enforce user/group permissions and root directory settings, but they are not required for basic mounting.DNS Round-Robin: If multiple mount targets exist, EC2 instances can use DNS round-robin to distribute load (but latency is still optimized by AZ-local mount targets).