Schedulers¶

Scheduling storage one resource at a time...

---

Overview¶

This page reviews the scheduling systems supported by libStorage.

Docker¶

libStorage's 'Docker Integration Driver is compatible with 1.10+.

However, Docker 1.10.2+ is suggested if volumes are shared between containers or interactive volume inspection requests are desired via the /volumes, /volumes/{service}, and /volumes/{service}/{volumeID} resources.

Please note that this is not the same as Docker's Volume Plug-in. libStorage does not provide a way to expose the Docker Integration Driver via the Docker Volume Plug-in, but REX-Ray, which embeds libStorage, does.

Example Configuration¶

Below is an example config.yml that can be used. The volume.mount.preempt is an optional parameter here which enables any host to take control of a volume irrespective of whether other hosts are using the volume. If this is set to false then plugins should ensure safety first by locking the volume from to the current owner host. We also specify docker.size which will create all new volumes at the specified size in GB.

libstorage:
  host: unix:///var/run/libstorage/localhost.sock
  integration:
    volume:
      mount:
        preempt: true
      create:
        default:
          size: 1 # GB
  server:
    endpoints:
      localhost:
        address: unix:///var/run/libstorage/localhost.sock
    services:
      virtualbox:
        driver: virtualbox
        virtualbox:
          endpoint:       http://10.0.2.2:18083
          tls:            false
          volumePath:     $HOME/VirtualBox/Volumes
          controllerName: SATA

Configuration Properties¶

The Docker integration driver adheres to the properties described in the section on an Integration driver's volume-related properties.

Please note that with Docker 1.9.1 or below, it is recommended that the property libstorage.integration.volume.remove.disable be set to true in order to prevent Docker from removing external volumes in-use by containers that are forcefully removed.

Caveats¶

If you restart the process which embeds libStorage and hosts the Docker Volume Plug-in while volumes are shared between Docker containers, then problems may arise when stopping one of the containers sharing the volume.

It is suggested to avoid stopping these containers at this point until all containers sharing the volumes can be stopped. This will enable the unmount process to proceed cleanly.