Three EC2 instances running the same Linux content management system, spread across three Availability Zones, all need read and write access to one uploads directory with ordinary POSIX file permissions. Which storage service should they use?
AWS Certified Cloud Practitioner (CLF-C02), objective 3. Cloud technology and services medium
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The options
Correct Amazon EFS
Correct. EFS is a managed NFS file system that many instances can mount at the same time, across Availability Zones, and it grows and shrinks automatically as files are added and removed.
Not correct One Amazon EBS volume attached to all three instances
Wrong. An EBS volume lives in a single Availability Zone and normally attaches to a single instance. The Multi-Attach feature exists but is limited to certain volume types within one zone and still needs a cluster-aware file system to be safe.
Not correct Instance store volumes on each instance
Wrong on both counts. Each instance would see its own local disk rather than a shared one, and the contents are lost when an instance stops.
Not correct Amazon FSx for Windows File Server
Wrong service for this platform. It provides SMB file shares with Active Directory integration for Windows workloads, which is the right answer to the same question asked about a Windows fleet.
Why
Match the service to how many machines need the data at once. EBS: block storage, one Availability Zone, effectively one instance — boot volumes and databases. EFS: NFS for Linux, mounted by many instances across zones, elastic capacity. FSx: managed versions of file systems people already use — FSx for Windows File Server for SMB and Active Directory, FSx for Lustre for high-performance computing. If more than one machine must see the same files at the same time, you want a file system, not a volume.
Where this comes from
- Cited
- AWS exam guide task statement 3.6
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