Amazon EBS
EBS is the persistent block disk that attaches to an EC2 instance. It keeps data separate from the server lifecycle so it can serve as the operating system disk or the data disk even when the instance is restarted or replaced.
▶Architecture Diagram
🔍 StructureDashed line animations indicate the flow direction of data or requests
If a server can be replaced or restarted at any time, disks tied to that instance lifecycle take the data with them. Even when the application survives, storage that is not separated from the compute node makes recovery and scaling feel fragile.
Early cloud VMs had storage tightly coupled to instances, making data loss likely when servers disappeared. This is why a persistent block storage layer decoupled from compute, EBS, became necessary.
EBS provides persistent block storage volumes attached to EC2, with selectable types based on performance characteristics. Each volume is automatically replicated within the same Availability Zone to survive component failures, snapshots provide backups, and volumes can be reattached to other instances when needed.
EBS and EFS are both storage but differ in access patterns. EBS is a disk attached to a single instance, while EFS is a network filesystem mounted simultaneously by multiple instances. If you need a boot disk or a persistent volume for one server, look at EBS; if multiple compute resources must share the same files, look at EFS.
Commonly Compared Concepts
EFS
Shared File Storage
Both are storage, but EBS is a single-instance block disk while EFS is a filesystem shared by multiple instances.
S3
Unlimited Object Storage
Both store data, but EBS is a block disk attached to an instance while S3 is an independent API-based object store.
Well-suited when you need a persistent disk attached directly to a single compute instance, such as a boot volume, a database disk, or low-latency block I/O for one server. Not a good fit when multiple servers need to share the same files at once.