i think C should be the answer here, > Immediate accessibility is always required as the files contain critical business data that is not easy to reproduce If they do not explicitly mention that they are using Glacier Instant Retrieval, we should assume that Glacier -> takes more time to retrieve and may not meet the requirements

Most COST EFFECTIVE A: S3 Glacier Instant Retrieval is a new storage class that delivers the fastest access to archive storage, with the same low latency and high-throughput performance as the S3 Standard and S3 Standard-IA storage classes. You can save up to 68 percent on storage costs as compared with using the S3 Standard-IA storage class when you use the S3 Glacier Instant Retrieval storage class and pay a low price to retrieve data.

I think his assumption is correct because if you go to AWS documentation (https://aws.amazon.com/s3/storage-classes/glacier/) they clearly mention: "S3 Glacier Flexible Retrieval (formerly S3 Glacier)". So since this question doesn't specify the S3 Glacier class, then it would default to flexible retrieval (which ofc is not equal to Instant Retrieval).

You can make that assumption, but I think it would be wrong to make it. It does not state they are not using Glacier Instant Retrieval, and it's use would be the logical choice in this question, so I'm going for A

Yeah, Correct answer is C Because even if you assume the glacier class as Instant Retrieval. As per the Instant Retrieval class the immediate availability is only once per quarter. But in question it is clearly mentioned that the files should be immediately available anytime.

I think A is the answer, too. As S3 Glacier has 3 different classes and one of them is able to retrieve objects in milliseconds (Instant Retrieval). As no class has been specified, we can assume the on that meets requirements is selected.

Because it requires the lowest cost

onezone IA is cheap more than standard IA

"With S3 Glacier Instant Retrieval, you can save up to 68% on storage costs compared to using the S3 Standard-Infrequent Access (S3 Standard-IA) storage class, when your data is accessed once per quarter." Repeat: once per quarter! Plus if you keep all the data forever, even if on Glacier, it will cost more over time, than storing on a higher-cost storage for a period of time (here: 4 yrs). A does not delete.

why everybody assumed files must be deleted after 4 years. they said files "can" be deleted, and not "must" be deleted. ideally store the files in glacier after 4 years

*Immediate accessibility*

Keep in mind that "Glacier Flexible Retrieval" was previously named just "Glacier" (before they added Instant Retrieval). Regardless, they should have made it clear which Glacier class they are referring to since which one you select/assume can impact the correctness.

It should be C. The critical point is Immediate accessibility, only S3-IA can provide this.

In the other hand, you need to chose a tier when going for glacier, so my previous comment is not stating well. The question is tricky, I change my mind: agree with you on this one

"Immediate accessibility is always required". It can't be a, since Glacier Instant Retrieval has a limit of times the data can be accessed. "S3 Glacier Retrieval is the lowest cost archive storage with milliseconds retrieval for rarely accessed data. It is ideal for data that is accessed once or twice per quarter, and that requires immediate access."

immidiately accessible for 4 years bur rarely use - S3 standard IA. Correct answer is C

And we have a requirement (Most cost effective solution) hence A is the winner

COST EFFECTIVE IS THE DIAL WORD HERE. Answer is A

Glaciers usually take some time to retrieve

Use S3 Standard for 30 days, S3 Standard-IA after that, and retain objects for 4 years, then delete.

I'm going with C - the files might be required instantly even if rarely accessed.

Sorry! A also deletes... My bad... Still. once a quarter.

Why not A, with Glacier Instant Retrieval?

If Glacier class is not specified, I could assume it is refering to S3 Glacier Flexible Retrieval (formerly S3 Glacier). Then, the retrieval of data is not immediate as requested. The best option would be glacier Instant Retrieval, but it's not specified... so the best answer that fits is C.

S3 Glacier Instant Retrieval is more expensive than S3 Standard-IA for both storage and retrieval requests. S3 Standard-IA is 68% cheaper for storage than S3 Standard, while S3 Glacier Instant Retrieval is only 46% cheaper

S3 IA is the most suitable here.

If you do so more than ~4 times per year, you would pay more for Glacier Instant Retrieval than for S3 Standard.

Answer is A. Files are rarely accessed after 30 days and they require the MOST cost effective solution. Then the answer is Glacier.

I agree with this, since no specific information about Glacier modality, we can assume that Instant Retrieval is a possibility and as far as I know, this is cheaper than IA.

C is the answer. While both "S3 Standard-Infrequent Access" and "S3 One Zone-Infrequent Access" are storage classes on AWS S3 designed for data accessed infrequently, the key difference is that "S3 One Zone-IA" stores data in a single Availability Zone, making it cheaper but with a higher risk of data loss if that zone fails, whereas "S3 Standard-IA" spreads data across multiple Availability Zones for increased redundancy and availability; making it a better choice for critical data that needs to be readily accessible even if rarely accessed.

"Immediate accessibility is always required " and then "Cost effective"- that leaves us with C.

Option C is the most cost-effective solution because it provides immediate access for the first 30 days and optimizes for cost by transitioning the files to S3 Standard-IA after that period. It also complies with the company’s retention policy.