What is EBS?
Amazon Elastic Block Store (EBS) is AWS’s block storage service that provides persistent storage volumes for EC2 instances.
EBS volumes
An EBS volume is a network-attached storage device that can be attached to an EC2 instance.
- An EBS volume is bound to a specific Availability Zone (AZ).
- It can be detached from one instance and attached to another instance within the same AZ.
- Because it is network-attached storage, it is not physically tied to a single host machine.
- EBS volumes are persistent, so data remains even after the EC2 instance is stopped.
Note
Think of EBS as network storage for EC2, unlike Instance Store, which is physically attached and ephemeral.
EBS volume types
EBS provides different volume types for different performance and cost requirements.
SSD volumes
- gp2 / gp3: General Purpose SSD volumes that balance price and performance for a wide variety of workloads.
- io1 / io2: Highest-performance SSD volumes for mission-critical applications requiring low latency or high throughput. These support Provisioned IOPS (PIOPS) and are well-suited for database workloads.
HDD volumes
- st1: Low-cost HDD volume designed for frequently accessed, throughput-intensive workloads such as big data, data warehouses, and log processing.
- sc1: Lowest-cost HDD volume designed for less frequently accessed workloads.
Note
Only gp2, gp3, io1, and io2 can be used as boot volumes.
EBS Multi-Attach
EBS Multi-Attach allows the same EBS volume to be attached to multiple EC2 instances at the same time.
- Available only for the io1 / io2 volume families.
- All attached instances must be in the same AZ.
- Each attached instance can have read and write access to the volume.
- The file system used must be cluster-aware.
Important
EBS Multi-Attach requires a cluster-aware file system. Traditional file systems such as XFS or ext4 are not suitable for this use case.
EBS encryption
EBS encryption protects data at rest and in transit between the EC2 instance and the EBS volume.
- EBS encryption has minimal impact on latency and performance.
- It is recommended to enable encryption for EBS volumes.
- Encryption helps protect sensitive data stored on the volume and in snapshots created from it.
Tip
A good default is to assume that EBS volumes should be encrypted unless there is a specific reason not to.
Tutorial: Moving EBS volumes across AZs and Regions
Because EBS volumes are tied to a single AZ, you cannot directly move a volume across AZs or Regions.
Steps
- To move an EBS volume to another AZ, you must first create a snapshot.
- Then, create a new volume from that snapshot in the target AZ.
- Snapshots can also be copied across Regions.
Important
EBS volumes are AZ-scoped. For exam questions, if you need to move a volume across AZs or Regions, the answer usually involves a snapshot.