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EBSAmazon Elastic Block Store

StorageCore service · full depthFree while we build the libraryChecked against AWS docs · 15 Sept 2026

Block storage volumes for EC2 instances: a disk that outlives the instance, lives in one Availability Zone, and is backed up with snapshots.

In the examsSolutions Architect – AssociateHIGHSolutions Architect – ProfessionalMEDDeveloper – AssociateLOWSysOps Administrator – AssociateHIGHSecurity – SpecialtyMED

Where EBS takes you6 steps, all open

I know the problem it solves
I can picture it
I know how it fails
I know when to choose it
I can use it in a design
I can answer an exam question

What & why

A disk that outlives the instance

EBS gives an EC2 instance block storage: a volume that works like a hard drive attached to it. It persists independently of the instance, so its data survives a stop and a start, and it is replicated within its Availability Zone so that one failed hardware component does not lose it.

One zone, usually one instance. A volume attaches only to instances in its own Availability Zone, normally one at a time; only io1 and io2 volumes can be shared, with Multi-Attach. AWS does not back volumes up for you: the snapshots are yours to take.

Reach for it when

an instance needs a boot volume, or a disk for a database
data must survive the instance stopping
a workload needs guaranteed IOPS or throughput
a disk must grow or change type without stopping the instance

It is the wrong tool when

instances in several zones must share the same files: that is EFS
objects are served over HTTP, in any amount: that is S3
the data is scratch space you can lose: instance store comes with the instance

Mental model

An external drive that stays in its room

An external hard drive that plugs only into computers in the same room. You pick a fast solid-state drive or a cheaper spinning one. Copy it to the building's archive, and you can make a new drive from that copy in any room of the building, or send the copy to another building.

The driveblock storage for an instanceEBS volume

The roomwhere the volume and its instance must beAvailability Zone

Solid-state or spinningthe performance you pay forgp3, io2, st1, sc1

A copy in the building's archivea point-in-time backup, usable in any zoneSnapshot

Copying only what changedeach snapshot saves the changed blocksIncremental

Throwing the drive out with the computerwhether a volume goes with its instanceDeleteOnTermination

How it works

Type, zone, attach, snapshot

Choose a typeGeneral Purpose SSD (gp3, gp2) for most workloads, Provisioned IOPS SSD (io2, io1) for sustained IOPS, and HDD (st1, sc1) for large sequential reads.
Create it in a zoneThe volume lives in one Availability Zone, where it is replicated, and attaches to instances there.
Attach and use itIt appears as a block device to format with a file system. Its size, type and IOPS can be changed while it is in use.
Snapshot itSnapshots are incremental and stored in S3 across the Region's zones, so they can become volumes in any zone, or be copied to another Region.

gp3 baseline: 3,000 IOPSand 125 MiB/s, at any size
gp3 maximum: 80,000 IOPS2,000 MiB/s, up to 64 TiB
io2 Block Express: 256,000 IOPS99.999% durability
gp2: 3 IOPS per GiB100 to 16,000; bursts to 3,000
Multi-Attach: Up to 16Nitro instances, io1 or io2, one zone
st1 and sc1: Not bootableHDD, for throughput

Architecture

A way out of the zone

The volume never leaves AZ a. Its snapshots are stored across the Region, so one can become a new volume in AZ b.

Snapshots on a schedule. Amazon Data Lifecycle Manager or AWS Backup can take them automatically, since AWS takes none for you.

Encryption follows the data. Snapshots of an encrypted volume are encrypted, and so are the volumes restored from them.

Failure simulation

Get the data somewhere else

Same zone
A volume attaches only to instances in its own Availability Zone.
Snapshot
Stored in S3 across the Region's zones, so it can become a volume in any of them, or be copied to another Region.
New volume
Created from the snapshot in the zone you choose, as an exact copy of the data when the snapshot was taken.
Attach
To an instance in that zone.

Pick a case to follow the data through each check.

Instance store is different. It is erased when the instance stops. An EBS volume keeps its data through a stop and a start.

When the instance is terminated, each volume's DeleteOnTermination setting decides its fate. By default the root volume created at launch is deleted, and a data volume attached later is kept, and still charged.

Security

Encryption end to end

Encrypt with KMS. Encryption covers data at rest, data moving between the instance and the volume, the snapshots taken from it and the volumes restored from them.

Encryption by default. Turn it on, and new volumes, and snapshot copies made from unencrypted snapshots, are always encrypted.

No switch in place. An unencrypted volume cannot be encrypted directly: snapshot it, then create an encrypted volume or an encrypted snapshot copy from the snapshot.

Share snapshots with care. A snapshot can be shared with chosen accounts or made public, but an encrypted one can never be public, and the account you share it with needs permission to use its KMS key.

Cost

How you are charged, not what it costs today

Provisioned, not used. A volume is charged for every GB you provision, each month, until you delete it, however much is written to it.

Performance above the baseline. gp3 includes 3,000 IOPS and 125 MiB/s at any size; more is charged.

Snapshots are charged for the data they store, which is only what changed. A copy to another Region starts as a full copy.

Fast snapshot restore is charged for each minute it is enabled, for each snapshot in each zone, with a one-hour minimum.

Forgotten volumes still cost money. One kept after its instance is terminated is charged until it is deleted.

Prices change, so none are printed here. Check the EBS pricing page on aws.amazon.com.

Comparison

Six volume types, and three kinds of instance storage

Type	Media	Max IOPS	Max throughput	Choose it when
gp3	SSD	80,000	2,000 MiB/s	Most workloads and boot volumes
gp2	SSD	16,000	250 MiB/s	Existing volumes; gp3 is 20 percent lower per GiB
io2 Block Express	SSD	256,000	4,000 MiB/s	Sub-millisecond latency, sustained IOPS, Multi-Attach
io1	SSD	64,000	1,000 MiB/s	Older Provisioned IOPS volumes
st1	HDD	500	500 MiB/s	Big data, data warehouses and logs: large sequential reads
sc1	HDD	250	250 MiB/s	Rarely read data, where the lowest storage cost matters

Storage	Survives a stop	Used by	Where it lives
EBS volume	Yes	One instance, or up to 16 with Multi-Attach	One Availability Zone
Instance store	No: erased on stop	Its own instance only	The instance's host
EFS file system	Yes: it is separate from instances	Many instances, containers and functions at once	A Region, or one zone

SAA traps

The phrase in the question, and what it means

attach the volume to an instance in another Availability ZoneSnapshot it, then create a volume in that zone

A volume attaches only to instances in its own zone.

sub-millisecond latency and sustained IOPS beyond what gp3 givesio2 Block Express

Up to 256,000 IOPS and 99.999% durability, with average latency under 500 microseconds.

the most cost-effective SSD for most workloadsgp3

3,000 IOPS and 125 MiB/s at any size, at a lower price per GiB than gp2.

large sequential reads for a data warehouse, at low costThroughput Optimized HDD, st1

Built for throughput rather than IOPS, and never a boot volume.

encrypt an existing unencrypted volumeSnapshot it, then make an encrypted copy or volume

Encryption cannot be turned on in place.

a clustered application needs one volume shared by several instancesMulti-Attach on io2

Up to 16 Nitro instances in the same zone, with a cluster-aware file system.

the data was lost when the instance was terminatedDeleteOnTermination

The root volume created at launch is deleted with the instance by default.

keep backups in another Region for disaster recoveryCopy the snapshots to that Region

A volume never leaves its zone, but its snapshots can be copied.

a volume restored from a snapshot is slow at firstFast snapshot restore

The volume is fully initialised when it is created, so first reads are not slower.

Scenario

Exam style, marked when you answer

A company runs a self-managed database on an EC2 instance in us-east-1a, with its data on an EBS volume. For disaster recovery, it must be able to bring the database up in us-east-1b if us-east-1a fails. What should a solutions architect do?

Practice

Fill the gap, the way the challenges work

A self-managed database on one EC2 instance needs block storage for its data files, with sub-millisecond latency and sustained high IOPS. The data must survive the instance being stopped, and be backed up every night. What holds the data files?

EC2· Database serverPick a service belowAWS Backup· Nightly backups

Quick revision

The night before the exam

Scope: One Availability Zone, replicated within it; attaches only there.
gp3: 3,000 IOPS and 125 MiB/s included; up to 80,000 IOPS.
io2 Block Express: Up to 256,000 IOPS, sub-millisecond, 99.999% durable.
HDD: st1 for throughput, sc1 for cold data; neither can boot.
Snapshots: Incremental, in S3, restorable in any zone, copyable to other Regions.
Encryption: At rest, to the instance and in snapshots; never switched on in place.
Multi-Attach: io1 and io2, up to 16 Nitro instances, same zone.
Termination: The root volume from launch is deleted by default.

This whole page is free right now.The AWS library is still being written, so every page of it is open to everyone while that lasts. It becomes a paid bundle later; what you read today costs you nothing.

Checked against

Every fact on this page was checked against AWS’s own documentation on 15 Sept 2026. If AWS has changed something since, its page is the one to trust.