Amazon S3 - Valid Statements

Answer: C and D.

Options A and B are incorrect because both of them are outdated features of Amazon S3.

Option C is CORRECT because Amazon S3 provides strong read-after-write consistency for PUTs and DELETEs of objects in your Amazon S3 bucket in all AWS Regions.

This applies to both writes to new objects as well as PUTs that overwrite existing objects and DELETEs.

Option D is CORRECT because Amazon S3 does not support object locking for concurrent writers.

If two PUT requests are simultaneously made to the same key, the request with the latest timestamp wins.

If this is an issue, you will need to build an object-locking mechanism into your application.

Option E is incorrect because atomic updates across keys are not possible.

For example, if you PUT to an existing key from one thread and perform a GET on the same key from a second thread concurrently, you will get either the old data or the new data, but never partial or corrupt data.

Reference:

https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcome.html#ConsistencyModel

Amazon S3 is a cloud-based object storage service offered by Amazon Web Services (AWS). It is designed to store and retrieve any amount of data from anywhere on the web. S3 is used for various purposes, such as backup and disaster recovery, content distribution, and big data analytics.

Let's discuss each option in detail:

A. S3 provides strong read-after-write consistency ONLY for PUTs. This statement is partially correct. When a new object is uploaded to S3, it is immediately available for read-after-write consistency, which means that any subsequent GET request to read the object will return the latest version of the object. However, this is not true for updates. When an existing object is updated, S3 provides eventual consistency, which means that it may take some time for the updates to be visible across all S3 locations. Therefore, option A is incorrect.

B. S3 provides eventual consistency for PUTs or DELETES. This statement is correct. As mentioned earlier, when an existing object is updated or deleted, S3 provides eventual consistency. This means that it may take some time (usually a few seconds) for the updates or deletions to be visible across all S3 locations. Therefore, option B is correct.

C. S3 provides strong read-after-write consistency for PUTs and DELETEs. This statement is incorrect. S3 provides strong read-after-write consistency for new objects (PUTs), but not for updates or deletions. Therefore, option C is incorrect.

D. S3 does not support object locking for concurrent writers. This statement is correct. S3 does not support object locking for concurrent writers. This means that multiple users can write to the same object at the same time, which can lead to conflicts and data corruption. Therefore, option D is correct.

E. Atomic updates across keys are possible. This statement is incorrect. S3 does not support atomic updates across keys. Therefore, option E is incorrect.

In conclusion, the correct statements about Amazon S3 are:

• S3 provides eventual consistency for PUTs or DELETES.
• S3 does not support object locking for concurrent writers.