The solution must maintain high availability throughout the data lifecycle. S3 One Zone-Infrequent Access (S3 One Zone-IA) stores data in a single Availability Zone and is therefore not a highly available solution, which eliminates options A and D. For data accessed infrequently between 6 months and 2 years, S3 Standard-Infrequent Access (S3 Standard-IA) is the correct choice as it maintains multi-AZ resilience. For data older than 2 years that is accessed only once or twice annually, S3 Glacier Deep Archive is the most cost-effective storage class. It is designed for long-term data archiving and retention at the lowest cost, fitting the access pattern perfectly.

1. Amazon S3 User Guide

"Amazon S3 storage classes." This document details the use cases

availability

and durability of each S3 storage class. It specifies that S3 Standard-IA is for "long-lived

infrequently accessed data" and maintains the same high availability (99.9%) and durability as S3 Standard by storing data across multiple Availability Zones. In contrast

it states S3 One Zone-IA is for "recreatable

infrequently accessed data" and is stored in a single AZ

making it unsuitable for this scenario's high availability requirement. It also identifies S3 Glacier Deep Archive as the "lowest-cost storage class" for long-term archive.

2. Amazon S3 User Guide

"Managing your storage lifecycle." This guide explains how to create lifecycle configuration rules to transition objects between storage classes. The scenario described in the question is a primary use case for S3 Lifecycle policies

transitioning objects to more cost-effective storage tiers based on age and access patterns. The path from S3 Standard -> S3 Standard-IA -> S3 Glacier Deep Archive is a common and recommended lifecycle configuration for cost optimization.

3. AWS Documentation

"Comparing the Amazon S3 storage classes." The comparison table in this official documentation explicitly shows S3 Standard-IA has "≥ 3" Availability Zones

while S3 One Zone-IA has "1" Availability Zone. This directly supports the elimination of options A and D. The table also lists the primary use case for S3 Glacier Deep Archive as "Archiving data that rarely

if ever

is accessed

" which aligns with the question's scenario for data older than two years.