devicemapper
A block-level Docker storage driver built on Linux thin provisioning, deprecated and removed in Docker Engine 25.
In more detail
loop-lvm mode used loopback files and was for testing only; direct-lvm mode used a dedicated block device, set with dm.* storage options, for production. It was common on older RHEL and CentOS hosts. The Docker Certified Associate exam still asks how to configure it.
Related terms
- storage driver — The part of the Docker daemon that decides how image layers and container writable layers are stored on disk.
- OverlayFS — The Linux union filesystem Docker uses to stack image layers into a container root directory.
- aufs — A union filesystem storage driver used by early Docker on Ubuntu, removed in Docker Engine 24.
Taught in
- One Comma, No Engine: Installing And Configuring Docker Engine — Docker Certified Associate (DCA) Exam Prep
- Security Sprint: Eight Questions On Defaults, Trust And Access — Docker Certified Associate (DCA) Exam Prep
- Two Containers, How Much Disk? Storage Drivers, Layers And devicemapper — Docker Certified Associate (DCA) Exam Prep
- Orders That Vanished: Volumes, Shared Storage And Cleanup — Docker Certified Associate (DCA) Exam Prep
- Storage Sprint: Eight Questions On Layers, Drivers And Volumes — Docker Certified Associate (DCA) Exam Prep
- Friday, Nine In The Morning: The Mock Exam And Its Report — Docker Certified Associate (DCA) Exam Prep
- The Night Before: Final Review And Exam Day — Docker Certified Associate (DCA) Exam Prep