Which statement best describes S3-style object storage durability and read-after-write behavior?

Which statement best describes S3-style object storage durability and read-after-write behavior?

• A. Extremely high durability; read-after-write is guaranteed for new PUTs in many cases; overwrites/deletes may be eventually consistent depending on service.
• B. Low durability; read-after-write is never guaranteed.
• C. All operations are strongly consistent worldwide.
• D. Read-after-write is guaranteed for all operations, including overwrites.

Answer: (A)

S3-style object storage is built for extremely high durability, meaning data is protected against loss even in the face of failures. It achieves this by replicating data across multiple devices and facilities. Read-after-write semantics come into play for new objects: after you PUT a new object, you can read it back and expect to see it right away in many cases. But when you overwrite an existing object or delete one, those operations may not be visible everywhere immediately—the system can be eventually consistent, with updates propagating over time. So the best description is that durability is extremely high, read-after-write is guaranteed for new PUTs in many cases, and overwrites/deletes may be eventually consistent depending on the service. The other statements—claiming low durability, or that all operations are strongly consistent worldwide, or that read-after-write is guaranteed for all operations including overwrites—do not match how S3-style storage typically behaves.

S3-style object storage is built for extremely high durability, meaning data is protected against loss even in the face of failures. It achieves this by replicating data across multiple devices and facilities. Read-after-write semantics come into play for new objects: after you PUT a new object, you can read it back and expect to see it right away in many cases. But when you overwrite an existing object or delete one, those operations may not be visible everywhere immediately—the system can be eventually consistent, with updates propagating over time. So the best description is that durability is extremely high, read-after-write is guaranteed for new PUTs in many cases, and overwrites/deletes may be eventually consistent depending on the service. The other statements—claiming low durability, or that all operations are strongly consistent worldwide, or that read-after-write is guaranteed for all operations including overwrites—do not match how S3-style storage typically behaves.