s3 one zone ia and s3 standard ia

S3 One Zone IA vs S3 Standard IA – Which One to Use and When?

Recently many learners who are preparing for AWS Certified Solutions Architect Associate exam or AWS SysOps Administrator Associate exam have enquired us about distinct use cases for S3 One Zone IA and S3 Standard IA storage classes. So, to help you understand the difference (in terms of usage) between these similar storage classes, we will explain two use cases, in this article.

The use cases for these 2 storage classes sound a bit ambiguous. Let us dive deep into this topic to make things clear with a practical example.

S3 Storage Classes

S3 One Zone IA and S3 Standard IA Storage Classes

To understand the difference between the usage of S3 One Zone IA and S3 Standard IA storage classes, we will consider the real-life examples. Here we will discuss two scenarios for the S3 One Zone IA and S3 Standard IA storage classes.

Use Case Scenario – 1

An organization uses an S3 bucket for logging all their application logs on to an S3 bucket and they are not storing these logs elsewhere other than the S3 bucket. The files vary in the range between 10 MB-500 MB in size and are not accessed regularly. They need these log files once in a while to troubleshoot the application issues. The application team needs last 60 days’ log files to be immediately available when required. Logs older than 60 days need to be kept for reference but there is no need to access it immediately. Which of the S3 storage class is apt for the scenario described, ensuring the most economical way to store these files?

Why S3 One Zone-IA storage Class is Not Suitable for the Above Scenario

Let us analyze the scenario in detail.

The scenario states that the organization wants to write application log files to S3 buckets and they are not intending to store it elsewhere and that is the only copy available. We have been asked to implement an appropriate storage class to satisfy the criteria and to ensure low-cost billing.

For this scenario, S3 OneZone-IA is not appropriate because S3 One Zone-IA is intended for use cases with infrequently accessed data that is re-creatable, such as storing secondary backup copies of on-premises data or for storage that is already replicated in another AWS Region for compliance or disaster recovery purposes.

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Since we are dealing with data that cannot be replicated, we cannot ensure the availability of the data when required (in case of a natural disaster in that zone) if we use One Zone-IA storage class.

Hence for this use case, it would be appropriate to use S3 Standard-IA Storage class for 60 days and then use Life Cycle Management to move the files that are older than 60 days to S3 Glacier storage. This will ensure the availability of the logs as per the scenario and it will also ensure the most economical billing for this storage requirement.

Now let us summarize these S3 One Zone IA and S3 Standard IA storage classes along with the standard S3 storage Class (side-by-side comparison):

Factor of Difference S3 Standard S3 Standard IA S3 One Zone IA
Durability 99.999999999% 99.999999999% 99.999999999%
Availability 99.99% 99.9% 99.5%
Stored in AZ >=3 >=3 1
Minimum Storage Duration Cost N/A 30 days 30 days
Retrieval fee N/A Per GB retrieved Per GB retrieved
Lifecycle Transitions Yes Yes Yes


One major difference between S3 Standard IA and S3 One Zone IA is that since  S3 One Zone-IA stores data in a single AWS Availability Zone, data stored in this storage class will be lost in the event of a failure of the Availability Zone. But One Zone IA offers a 20% subsidized cost compared to S3 Standard-IA.

Use Case Scenario – 2

An application is designed for users to upload images of famous monuments and an S3 bucket is used to store these images. Another application is designed to process these images in various formats and create thumbnails of these images and tag the images as per the country. And store it in another S3 bucket and these images are not accessed on a regular basis. You have been asked to choose an appropriate Storage class which is cost-effective for storing the thumbnails.

Why S3 One Zone-IA storage Class is Suitable for the Above Scenario

In this scenario, we can make use of the S3 One Zone-IA Storage class since these thumbnails can be created from the original images. Since the data can be re-created, we can make use of the One Zone-IA storage class which offers a reduced cost associated with it.

Other Helpful Resources:

Simplifying Ephemeral Ports with Example

Route 53 Policies: Latency-based Routing vs Geolocation Routing


Important Complementary Information

Before you go for the exam, we also recommend you to read about the following Storage class as well.

Recently S3 has begun to offer a new storage class named Amazon S3 Intelligent-Tiering storage class that is specifically designed to change the storage class of S3 in an automatic manner by analyzing the usage pattern of the objects stored in it. It uses two tiers where one is optimized for frequent access and another is the low-cost tier for infrequent access. Amazon S3 Intelligent-Tiering storage class automatically moves objects between two access tiers depending on the actual usage.  

As per AWS documentation, this Intelligent Tiering storage class is considered the ideal storage class for the long-lived data along with access patterns that unpredictable or unknown. It is possible to configure the S3 Storage Classes at the object level and only a single bucket has the capability to contain objects stored in S3 Intelligent-Tiering, S3 Standard, S3 Standard-IA, S3 One Zone-IA, and S3 One Zone-IA storage classes.

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Bottom Line

Hope the above analysis has the required clarity that makes you clearly understand the difference between two similar sounding storage classes (in terms of usages). It is required to understand the concept of S3 Storage classes if you are preparing for Certified Solutions Architect or SysOps Administrator exam.

Besides, to help you with your preparation, we also offer online course and practice tests for AWS Certified Solutions Architect Associate exam and AWS Certified SysOps Administrator Associate exam. Whizlabs study and practice material are prepared by the subject matter experts and certified professionals that will help you prepare and pass the certification exams.

Start your preparation now to become an AWS Certified professional.

In case you have any confusion about S3 Storage Classes, just mention in the comment section below or write in Whizlabs Forum to get it resolved by the experts.

About Pavan Gumaste

Pavan Rao is a programmer / Developer by Profession and Cloud Computing Professional by choice with in-depth knowledge in AWS, Azure, Google Cloud Platform. He helps the organisation figure out what to build, ensure successful delivery, and incorporate user learning to improve the strategy and product further.

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