EC2 Instance Storage

1. What’s an EBS volume?

An EBS (Elastic Block Store) volume is a network drive you can attach to your instances while they run.

• It allows your instances to persist data, even after their termination.
• They can only be mounted to one instance at a time (at the Cloud Practitioner level).
• They are bound to a specific Availability Zone.
• Analogy: think of them as a “network USB stick”.

Going a level deeper:

• It’s a network drive, not a physical drive — it uses the network to communicate with the instance, so there may be a bit of latency.
• It can be detached from one EC2 instance and attached to another quickly.
• It’s locked to an Availability Zone: an EBS volume in us-east-1a cannot be attached to an instance in us-east-1b. To move a volume across, you first need to snapshot it.
• It has provisioned capacity (size in GB, and IOPS). You get billed for all the provisioned capacity, and you can increase the capacity of the drive over time.

Exam tip

Two AZ facts decide most EBS questions: a volume lives in one AZ, and it attaches to one instance at a time. The way across an AZ boundary is always a snapshot.

Real-world example

The deck’s picture: in us-east-1a one instance has a 10 GB and a 100 GB volume, another has a 50 GB volume; in us-east-1b there is a 50 GB volume attached and a 10 GB volume sitting unattached. An unattached volume is perfectly normal — and still billed.

2. Delete on Termination attribute

This attribute controls the EBS behaviour when an EC2 instance terminates.

• By default, the root EBS volume is deleted (attribute enabled).
• By default, any other attached EBS volume is not deleted (attribute disabled).
• It can be controlled through the AWS Console or the AWS CLI.
• Use case: preserve the root volume when the instance is terminated.

3. EBS Snapshots

A snapshot is a backup of your EBS volume at a point in time.

• It is not necessary to detach the volume to take a snapshot, but it is recommended.
• You can copy snapshots across AZ or Region — which is exactly how a volume gets moved.

Snapshot features

• EBS Snapshot Archive — move a snapshot to an “archive tier” that is 75% cheaper; restoring from the archive takes 24 to 72 hours.
• Recycle Bin for EBS Snapshots — set up rules to retain deleted snapshots so you can recover them after an accidental deletion; you specify a retention period from 1 day to 1 year.

Exam tip

Archive = 75% cheaper but 24–72 hours to restore. Recycle Bin = protection against accidental deletion, retention 1 day to 1 year. Those two numbers are the ones that show up in answer options.

4. AMI — Amazon Machine Image

• An AMI is a customization of an EC2 instance: you add your own software, configuration, operating system, monitoring and so on.
• Faster boot / configuration time, because all your software is pre-packaged.
• AMIs are built for a specific Region — and can be copied across Regions.

You can launch EC2 instances from:

• A Public AMI — AWS provided.
• Your own AMI — you make and maintain them yourself.
• An AWS Marketplace AMI — an AMI someone else made (and potentially sells).

The AMI process, from an EC2 instance

1. Start an EC2 instance and customize it.
2. Stop the instance (for data integrity).
3. Build an AMI — this will also create EBS snapshots.
4. Launch instances from that AMI — including in another AZ.

Real-world example

You customize an instance in us-east-1a, build a custom AMI from it, then launch new instances from that AMI in us-east-1b. Everything you installed is already there at first boot — no User Data script waiting to run.

5. EC2 Image Builder

• Used to automate the creation of Virtual Machines or container images.
• Automates the creation, maintenance, validation and testing of EC2 AMIs.
• Can be run on a schedule — weekly, whenever packages are updated, and so on.
• It is a free service — you only pay for the underlying resources.

The flow: EC2 Image Builder creates a Builder EC2 instance, applies build components (customizing the software on the instance), creates a new AMI, launches a Test EC2 instance to run a test suite (is the AMI working, secure?), and then distributes the AMI — potentially to multiple Regions.

Exam tip

“Free service, you only pay for the underlying resources” is exactly the phrasing the exam uses for EC2 Image Builder. Any scenario about automatically rebuilding and testing golden images points here.

6. EC2 Instance Store

EBS volumes are network drives with good but “limited” performance. If you need a high-performance hardware disk, use EC2 Instance Store.

• Better I/O performance — very high IOPS, because the disk is physically attached to the host.
• EC2 Instance Stores lose their storage if the instance is stopped — they are ephemeral.
• Good for buffer / cache / scratch data / temporary content.
• Risk of data loss if hardware fails.
• Backups and replication are your responsibility.

Exam tip

Any answer that pairs “highest possible IOPS” with “data must survive a stop” is a contradiction. Instance Store gives the IOPS but is ephemeral; EBS persists but is a network drive.

7. EFS — Elastic File System

• A managed NFS (network file system) that can be mounted on 100s of EC2 instances.
• Works with Linux EC2 instances, in multi-AZ.
• Highly available, scalable, expensive (3x gp2), pay per use, no capacity planning.

EBS vs EFS

	EBS	EFS
Attachment	One instance at a time	100s of instances
Scope	One Availability Zone	Multi-AZ, via mount targets in each AZ
Moving across AZ	Snapshot and restore	Not needed — it already spans AZs
Capacity	Provisioned, and billed for what’s provisioned	No capacity planning, pay per use

EFS Infrequent Access (EFS-IA)

• A storage class cost-optimized for files not accessed every day.
• Up to 92% lower cost compared to EFS Standard.
• EFS automatically moves your files to EFS-IA based on the last time they were accessed.
• Enabled with a Lifecycle Policy — for example, move files not accessed for 60 days to EFS-IA.
• Transparent to the applications accessing EFS.

Real-world example

Three groups of instances in us-east-1a, us-east-1b and us-east-1c all mount the same EFS file system through a security group. No snapshot, no copying: every instance sees the same files, in every AZ. That is the thing EBS cannot do.

8. Shared Responsibility Model for EC2 Storage

AWS	You
Infrastructure	Setting up backup / snapshot procedures
Replication of data for EBS volumes and EFS drives	Setting up data encryption
Replacing faulty hardware	Responsibility for any data on the drives
Ensuring their employees cannot access your data	Understanding the risk of using EC2 Instance Store

9. Amazon FSx

Amazon FSx lets you launch third-party high-performance file systems on AWS, as a fully managed service. The three in the deck: FSx for Lustre, FSx for Windows File Server, and FSx for NetApp ONTAP.

FSx for Windows File Server

• A fully managed, highly reliable and scalable Windows native shared file system.
• Built on Windows File Server.
• Supports the SMB protocol and Windows NTFS.
• Integrated with Microsoft Active Directory.
• Can be accessed from AWS or from your on-premises infrastructure.

FSx for Lustre

• A fully managed, high-performance, scalable file storage for High Performance Computing (HPC).
• The name Lustre is derived from “Linux” and “cluster”.
• Use cases: machine learning, analytics, video processing, financial modeling.
• Scales up to 100s GB/s, millions of IOPS, sub-millisecond latencies.
• Can be linked to Amazon S3, and reached from compute instances in the Region or from a corporate data center.

Exam tip

The keyword split is clean: Windows / SMB / Active Directory → FSx for Windows File Server; Linux / HPC / machine learning / “millions of IOPS” → FSx for Lustre. And plain Linux file sharing between many EC2 instances → EFS, not FSx.

Quick recap

Concept	What to remember for the exam
EBS volume	Network drive attached to one EC2 instance at a time, mapped to one Availability Zone, provisioned capacity, billed on what’s provisioned
Delete on Termination	Enabled for the root volume by default, disabled for other attached volumes
EBS Snapshots	Point-in-time backup; the way to move a volume across AZ or Region
Snapshot Archive / Recycle Bin	Archive is 75% cheaper with a 24–72 hour restore; Recycle Bin retains deleted snapshots for 1 day to 1 year
AMI	Ready-to-use image with your customizations; Region-specific, copyable across Regions; Public, your own, or Marketplace
EC2 Image Builder	Automatically build, test and distribute AMIs on a schedule; free service, pay only for the underlying resources
EC2 Instance Store	High-performance hardware disk on the host; ephemeral — lost if the instance is stopped or terminated
EFS	Managed NFS for 100s of Linux instances across multiple AZs; no capacity planning; about 3x the price of gp2
EFS-IA	Cost-optimized class for infrequently accessed files, up to 92% cheaper, driven by a Lifecycle Policy
FSx for Windows	Managed Windows shared file system — SMB, NTFS, Active Directory
FSx for Lustre	Managed HPC Linux file system — 100s GB/s, millions of IOPS, links to Amazon S3