Open Stack

TripleO currently uses the default "loopback" docker storage device.
This is not recommended for production (see 'docker info').

We've been poking around with docker storage backends in TripleO for
almost 2 months now here:

 https://review.openstack.org/#/c/451916/

For TripleO there are a couple of considerations:

 - we intend to support in place upgrades from baremetal to containers

 - when doing in place upgrades re-partitioning disks is hard, if not
impossible. This makes using devicemapper hard.

 - we'd like to to use a docker storage backend that is production
ready.

 - our target OS is latest Centos/RHEL 7

As we approach pike 2 I'm keen to move towards a more production docker
storage backend. Is there consensus that 'overlay2' is a reasonable
approach to this? Or is it too early to use that with the combinations
above?

Looking around at what is recommended in other projects it seems to be
a mix as well from devicemapper to btrfs.

[1] https://docs.openshift.com/container-platform/3.3/install_config/in
stall/host_preparation.html#configuring-docker-storage
[2] http://git.openstack.org/cgit/openstack/kolla/tree/tools/setup_RedH
at.sh#n30


Dan