Amazon S3 Storage Classes

There are several storage classes available for Amazon S3. We'll learn about all of these in depth, but you have to know them for the exam.

The main classes are

Amazon S3 Standard-General Purpose,
S3-Infrequent Access,
S3 One Zone-Infrequent Access,
Glacier Instant Retrieval,
Glacier Flexible Retrieval,
Glacier Deep Archive, and
S3 Intelligent-Tiering.

When you create an object in S3, you can

choose its class.
You can also modify its storage class manually or
use S3 Lifecycle configurations to move objects between these classes automatically.

Think of it like managing files in an office.

Day 1 - 30 (On Your Desk): When a new file is created (e.g., a monthly report), it's placed in the S3 Standard class. Like a document on your desk, it's immediately accessible because you're actively using it.
Day 31 - 90 (In the Filing Cabinet): After a month, you're done with the report but might need to refer to it occasionally. A lifecycle rule automatically moves it to S3 Infrequent Access (IA). It's like putting the document in a nearby filing cabinet—still easy to get, but not taking up prime desk space.
Day 91+ (In the Archive Room): After a year, you probably won't look at that report again, but company policy requires you to keep it for 7 years. Another rule moves it to S3 Glacier Deep Archive. This is like sending the file to a long-term storage facility. It's very cheap to store, but it takes hours or days to retrieve if you ever need it.
After 7 Years (In the Shredder): Finally, a rule can be set to automatically and permanently delete the object after its required retention period is over.

How It Works

You define these rules on an S3 bucket. A typical lifecycle rule has two main types of actions:

Transition Actions: These rules move objects from one storage class to another. For example: "Move objects to S3 Infrequent Access 30 days after they are created."
Expiration Actions: These rules define when objects should be deleted. For example: "Permanently delete objects 2,555 days (about 7 years) after they are created."

In short, S3 Lifecycle configurations are a "set it and forget it" feature for automating your storage costs and data retention policies without any manual intervention.

Durability and Availability

Before we go into the classes, let's define the concepts of durability and availability.

Durability represents how many times an object is going to be lost by Amazon S3.

S3 has a very high durability of 11 9s (99.999999999%). This means that if you store 10 million objects on Amazon S3, you can expect to lose a single object once every 10,000 years.
The durability is the same for all S3 storage classes in Amazon S3.

Availability represents how readily available a service is, and this depends on the storage class.

For example, S3 Standard has 99.99% availability, which means the service may be unavailable for about 53 minutes a year. You need to take this into account when developing your applications.

The Storage Classes

S3 Standard - General Purpose

Used for frequently accessed data and is the default storage class.
It is 99.99% availability
It has Features low latency and high throughput.
It Can sustain two concurrent facility failures.
Use Cases: Big data analytics, mobile and gaming applications, and content distribution.

S3 Infrequent Access (Standard-IA)

It is used for data that is less frequently accessed but requires rapid access when needed.
It has a lower cost than S3 Standard, but you will have a cost on retrieval.
Availability is 99.9%.(less available than S3 Standard)
Use Cases: Disaster recovery and backups.

S3 One Zone - Infrequent Access (One Zone-IA)

Has high durability within a single Availability Zone (AZ) only.
Data will be lost if the AZ is destroyed.
Availability is lower at 99.5%. (less available than S3 Standard-IA)
Use Cases: Storing a secondary copy of backups of (maybe on-premises data), or data you can recreate.

Glacier Storage Classes

Glacier is a low-cost object storage meant for archiving and backup. The pricing is based on storage plus a retrieval cost.

Amazon S3 Glacier Instant Retrieval

Provides millisecond retrieval.
This is Great for data that's accessed once a quarter.
The minimum storage duration is 90 days. (So basically this is backup but you need to access it within milliseconds)

Amazon S3 Glacier Flexible Retrieval

It Offers 3 flexible retrieval times:

Expedited: You get the data back between 1 to 5 minutes
Standard: You get the data back between 3 to 5 hours
Bulk: You get the data back between 5 to 12 hours (and this is one is free of cost)

The minimum storage duration is 90 days.
Memory Trick to remember both S3 Glacier Instant and Flexible : - Instant means you retrieve the data instantly and - Flexible means you are willing to wait up to for example 12 hrs to retrieve the data.

Amazon S3 Glacier Deep Archive

Meant for long-term storage and offers the lowest cost.
Two retrieval tiers:

Standard: 12 hours
Bulk: 48 hours

(so be ready to wait for a lot of time)

The minimum storage duration is 180 days.

S3 Intelligent-Tiering

This class allows you to sit back and relax while S3 moves objects for you between access tiers based on usage patterns. It incurs a small monthly monitoring and auto-tiering fee, but there are no retrieval charges.

Frequent Access Tier: The default tier.
Infrequent Access Tier: For objects not accessed for 30 days.
Archive Instant Access Tier: For objects not accessed for over 90 days.
Archive Access Tier (Optional): Configurable from 90 to 700+ days.
Deep Archive Access Tier (Optional): Configurable for objects not accessed between 180 and 700+ days.

S3 Storage Classes Comparison

If you compare all the storage classes, you don't need to remember these numbers, but it's for you to make sense of what they are.

You get a durability of 11 9's everywhere.
As availability goes down, the fewer zones you have (see the table above).
The comparison shows things like the minimum storage duration.

You should take some time to look at the diagram on your own. You should understand it, but you should not remember it for the exam.

Pratham Mehta’s Notes