SAA-C03 practice question: Choosing shared storage (1 of 3)

Design High-Performing Architectures A free question from our original SAA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.

A media company runs a content management system on Linux EC2 instances in an Auto Scaling group across three Availability Zones. Every instance must read and write the same set of files at the same time, using standard Linux file permissions and file locking. The files total 300 GB today but grow unpredictably, and the team does not want to manage storage capacity. The files must stay available if one Availability Zone fails. Which storage option meets these requirements?

Choose one answer.

A. An Amazon EBS io2 volume with Multi-Attach turned on, attached to every instance in the Auto Scaling group.
B. An Amazon EFS Regional file system with mount targets in all three Availability Zones, mounted on every instance.
C. An Amazon FSx for Lustre Persistent SSD file system with provisioned storage, mounted on every instance in the group.
D. An Amazon FSx for Windows File Server Multi-AZ file system, mounted over SMB on every instance with cifs-utils.

Show the answer and explanation

Answer: B

A. Wrong: Multi-Attach lets up to 16 Nitro-based instances share a volume, but only in the same Availability Zone as the volume. Standard Linux file systems such as XFS and ext4 are also not designed for several servers writing at once; a cluster-aware file system would be needed. Learn more: Attach an EBS volume to multiple EC2 instances using Multi-Attach (opens in a new tab)
B. Right: Correct. EFS is a managed NFS file system that many Linux instances can share at once. A Regional file system stores data across several Availability Zones, so it survives the loss of one, and it grows and shrinks automatically as files are added and removed. Learn more: What is Amazon Elastic File System? (opens in a new tab)
C. Wrong: FSx for Lustre gives a shared, high-performance Linux file system, but SSD file systems keep data in a single Availability Zone and need their size set and managed. That fails both the zone-failure and the no-capacity-management requirements. Learn more: Deployment and storage class options for FSx for Lustre file systems (opens in a new tab)
D. Wrong: Linux clients can mount FSx for Windows File Server over SMB, and Multi-AZ covers a zone failure. However, file permissions are Windows ACLs, so the application's standard Linux permissions are not stored natively. A Linux-native NFS file system fits better. Learn more: Accessing your data (opens in a new tab)

Explanation

Three needs decide it: shared read-write access with Linux semantics, survival of a zone failure, and no capacity planning. Amazon EFS Regional file systems meet all three, with mount targets in each Availability Zone and elastic storage. EBS Multi-Attach is limited to one zone, FSx for Lustre SSD is single-zone and provisioned, and FSx for Windows File Server uses Windows permissions.

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SAA-C03 practice question: Choosing shared storage (1 of 3)

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