Exam AWS Certified Solutions Architect - Associate SAA-C02 topic 1 question 559 discussion

I think it should be B and E

For B , In the question, mentioned " ... building a shared storage solution for ..." Amazon EFS provides shared file storage for use with compute instances in the AWS Cloud and on-premises servers. Applications that require shared file access can use Amazon EFS for reliable file storage delivering high aggregate throughput to thousands of clients simultaneously. https://aws.amazon.com/efs/when-to-choose-efs/

It should be B and E. Good points are here for best solution. Why not D? AWS documentation says for DataSync the minimum frequency is 1 hour. Note the words in the question: "consistency in returning the new content as soon as the changes occur". So D cannot be the answer for this. https://docs.aws.amazon.com/datasync/latest/userguide/task-scheduling.html Why E? There is no other better solution. By eliminating all others, E is the answer. Also, the question has "The company plans to make frequent changes to the content.". The answer has a trick to say S3 and no-cache that solves the problem.

The solutions that meet the requirements of strong consistency and returning new content as soon as changes occur in a multi-Availability Zone deployment are: B. Create an Amazon Elastic File System (Amazon EFS) file system and mount it on the individual EC2 instances. Amazon EFS provides a fully managed, shared file system that supports strong consistency, allowing multiple EC2 instances to access and update the same files simultaneously. Changes made to the content will be immediately visible to all instances. E. Create an Amazon S3 bucket to store the web content, set the metadata for the Cache-Control header to no-cache, and use Amazon CloudFront to deliver the content. By configuring CloudFront with a no-cache header, you ensure that each request for content is always forwarded to the origin (S3 bucket) to check for any changes. This guarantees that the latest content is returned to users as soon as changes occur.

I know b is right, but why E? E is for static content

well, let me go into a bit deeper on the question. A x - Storage Gateway is more like we use for storage-storage back up. This time, actually EC2 is used for a server role. B o - shared file system (storage role), available in multi AZ C x - what!? EBS is a network storage for one EC2 at a time and not available for multi AZ D x - normally used for moving data between on-premises storage systems and AWS Storage services. (also we will definitely choose EFS so doesn't need DataSync) E o - In question, "frequent changes to the content." so doesn't need cache (I like this point). And S3 for web app... and delivery for CloudFront... I can't help thinking of those two when it comes to this question's situation.

The question does not say that it is a Linux instance.

why not D.. Coz... the EFS storage is already shared and all EC2 have access to this shared data.. so no need of AWS Data sync as a separate entity just to sync...

D is out because datasync can periodically replicate which is different from continuously

Question is about " .. tasked with the responsibility of building a shared storage solution" I believe Datasync is for migration purposes and letter A is connected individual to ec2 instances but the question also mentioned that instances are in auto scaling. With that I'll stick with best answers which is B and E

Key: --> 2 tier application , HA Requirement: consistent update & retrieval Distractors: C/D/E C is a distractor because EBS should be considered when we talk about RDS, as they are costly, have a limiation of mounting to instances & overhead of resizing if data keeps increasing D is a distractor as DataSync enables you to automate and accelerate online data transfers to AWS storage services E because Cloudfront is a CDN which means it will have TTL hence we cannot guarantee data consistency

The content is not mentioned to be static so B and D correct E - out because it is not related static cached content

I go for B&E

The answer should be A & B

B and D

its b and d for sure

B & D (EFS & DataSync) are correct. Reasons: B - is the easy one: EFS is for shared file system between EC2 instances D - I found two AWS articles that backs up this as the proper response: https://docs.aws.amazon.com/efs/latest/ug/trnsfr-data-using-datasync.html https://aws.amazon.com/premiumsupport/knowledge-center/datasync-transfer-efs-s3/ Explanation for D: "AWS DataSync is an online data transfer service that simplifies, automates, and accelerates moving and replicating data between on-premises storage systems, and also between AWS storage services. DataSync can copy data between (...) amazon EFS file systems.... You can also use DataSync to transfer files between two EFS file systems, including file systems in different AWS Regions and file systems owned by different AWS accounts. Using DataSync to copy data between EFS file systems, you can perform one-time data migrations, periodic data ingestion for distributed workloads, and automate replication for data protection and recovery."