docker-storage.md

Docker Storage

• If aufs is available, default to it, because it is the oldest storage driver. However, it is not universally available.

• If possible, the storage driver with the least amount of configuration is used, such as btrfs or zfs. Each of these relies on the backing filesystem being configured correctly.

• Otherwise, try to use the storage driver with the best overall performance and stability in the most usual scenarios.

  • overlay2 is preferred, followed by overlay. Neither of these requires extra configuration.
  • devicemapper is next, but requires direct-lvm for production environments, because loopback-lvm, while zero-configuration, has very poor performance.

• aufs, overlay, and overlay2 all operate at the file level rather than the block level. This uses memory more efficiently, but the container’s writable layer may grow quite large in write-heavy workloads.

• Block-level storage drivers such as devicemapper, btrfs, and zfs perform better for write-heavy workloads (though not as well as Docker volumes).

• For lots of small writes or containers with many layers or deep filesystems, overlay may perform better than overlay2.

• btrfs and zfs require a lot of memory.

• zfs is a good choice for high-density workloads such as PaaS.