Docker Storage Concepts
External
- https://docs.docker.com/engine/userguide/storagedriver/selectadriver
- https://docs.docker.com/engine/userguide/storagedriver/
Internal
Image Storage
The Docker server stores the layers that form images into a dedicated storage system, called the storage backend, managed by a pluggable storage driver.
Storage Driver
The Docker storage driver handles details related to how various layers, including the container layer interact with each other and how the container image is exposed. [Docker_Concepts[#Container|Containers]] and the images they are created from are stored in Docker’s storage back end. Where are images stored (docker images), and where are the running and stopped containers stored (docker ps)? The Docker server's storage backend communicates with the underlying Linux filesystem to build and manage the multiple image layers that combine to form a single image.
Some storage concepts, such as base device size, which essentially represents the container's root file system size, only apply to specific storage backend, device-mapper in this case, and they will be mentioned in the corresponding sections.
To determine what kind of storage backend is in use by a specific server instance, execute docker info. Storage backend details are provided as part of the result.