What is the key availability benefit of Amazon EFS compared with a single EBS volume?
Show answer and explanation
Answer: A
A standard EFS file system is created across the Availability Zones of its Region, and data is stored redundantly, so losing one zone does not take the file system offline. Multiple EC2 instances in different zones can mount the same file system at the same time.
EBS volumes, by contrast, are tied to a single Availability Zone, and instance store is ephemeral local disk.
Why the other options are wrong
- B. That describes the EFS One Zone storage class; the standard class is Regional and multi-AZ.
- C. EFS is generally more expensive per gigabyte than EBS, and the benefit here is availability, not price.
- D. Instance store is directly attached and far faster than a network file system, though it is not persistent.