That's correct - at ClusterHQ (makers of Flocker) we are focusing on using ZFS for volumes. ZFS itself is a copy-on-write filesystem, but we're using snapshots

That's correct - at ClusterHQ (makers of Flocker) we are focusing on using ZFS for volumes. ZFS itself is a copy-on-write filesystem, but we're using snapshots so that we can do send/recv between hosts, as opposed to using snapshots for the layers in a Docker image. Separately to the work we're doing, the guys at Gandi (a European hosting company) are working on ZFS support for Docker images - see https://github.com/docker/docker/pull/7901 https://github.com/docker/docker/pull/7901 Combining these two efforts could result in a pure ZFS-on-root Docker distribution, which uses ZFS with Flocker for volumes, and ZFS for the Docker images themselves. That would be pretty cool, IMHO. ;)