@@ -142,7 +142,7 @@ precedence over `HTTP_PROXY`.

 ### Daemon storage-driver option

 The Docker daemon has support for several different image layer storage

-drivers: `aufs`, `devicemapper`, `btrfs`, `zfs` and `overlay`.

+drivers: `aufs`, `devicemapper`, `btrfs`, `zfs`, `overlay` and `overlay2`.

 The `aufs` driver is the oldest, but is based on a Linux kernel patch-set that

 is unlikely to be merged into the main kernel. These are also known to cause

@@ -180,9 +180,14 @@ Linux kernel as of [3.18.0](https://lkml.org/lkml/2014/10/26/137). Call

 > inode consumption (especially as the number of images grows), as well as

 > being incompatible with the use of RPMs.

+The `overlay2` uses the same fast union filesystem but takes advantage of

+[additional features](https://lkml.org/lkml/2015/2/11/106) added in Linux

+kernel 4.0 to avoid excessive inode consumption. Call `dockerd -s overlay2`

+to use it.

+

 > **Note:**

-> It is currently unsupported on `btrfs` or any Copy on Write filesystem

-> and should only be used over `ext4` partitions.

+> Both `overlay` and `overlay2` are currently unsupported on `btrfs` or any

+> Copy on Write filesystem and should only be used over `ext4` partitions.

 ### Storage driver options

@@ -34,14 +34,14 @@ and all containers created by that daemon instance use the same storage driver.

  The table below shows the supported storage driver technologies and their

 driver names:

-|Technology    |Storage driver name  |

-|--------------|---------------------|

-|OverlayFS     |`overlay`            |

-|AUFS          |`aufs`               |

-|Btrfs         |`btrfs`              |

-|Device Mapper |`devicemapper`       |

-|VFS           |`vfs`                |

-|ZFS           |`zfs`                |

+|Technology    |Storage driver name    |

+|--------------|-----------------------|

+|OverlayFS     |`overlay` or `overlay2`|

+|AUFS          |`aufs`                 |

+|Btrfs         |`btrfs`                |

+|Device Mapper |`devicemapper`         |

+|VFS           |`vfs`                  |

+|ZFS           |`zfs`                  |

 To find out which storage driver is set on the daemon, you use the

 `docker info` command:

@@ -71,14 +71,15 @@ For example, the `btrfs` storage driver on a Btrfs backing filesystem. The

 following table lists each storage driver and whether it must match the host's

 backing file system:

-|Storage driver |Commonly used on |Disabled on                              |

-|---------------|-----------------|-----------------------------------------|

-|`overlay`      |`ext4` `xfs`     |`btrfs` `aufs` `overlay` `zfs` `eCryptfs`|

-|`aufs`         |`ext4` `xfs`     |`btrfs` `aufs` `eCryptfs`                |

-|`btrfs`        |`btrfs` _only_   |   N/A                                   |

-|`devicemapper` |`direct-lvm`     |   N/A                                   |

-|`vfs`          |debugging only   |   N/A                                   |

-|`zfs`          |`zfs` _only_     |   N/A                                   |

+|Storage driver |Commonly used on |Disabled on                                         |

+|---------------|-----------------|----------------------------------------------------|

+|`overlay`      |`ext4` `xfs`     |`btrfs` `aufs` `overlay` `overlay2` `zfs` `eCryptfs`|

+|`overlay2`     |`ext4` `xfs`     |`btrfs` `aufs` `overlay` `overlay2` `zfs` `eCryptfs`|

+|`aufs`         |`ext4` `xfs`     |`btrfs` `aufs` `eCryptfs`                           |

+|`btrfs`        |`btrfs` _only_   |   N/A                                              |

+|`devicemapper` |`direct-lvm`     |   N/A                                              |

+|`vfs`          |debugging only   |   N/A                                              |

+|`zfs`          |`zfs` _only_     |   N/A                                              |

 > **Note**

@@ -198,6 +199,24 @@ the guidance offered by the table below along with the points mentioned above.

 ![](images/driver-pros-cons.png)

+### Overlay vs Overlay2

+

+OverlayFS has 2 storage drivers which both make use of the same OverlayFS

+technology but with different implementations and incompatible on disk

+storage. Since the storage is incompatible, switching between the two

+will require re-creating all image content. The `overlay` driver is the

+original implementation and the only option in Docker 1.11 and before.

+The `overlay` driver has known limitations with inode exhaustion and

+commit performance. The `overlay2` driver addresses this limitation, but

+is only compatible with Linux kernel 4.0 and later. For users on a pre-4.0

+kernel or with an existing `overlay` graph, it is recommended to stay

+on `overlay`. For users with at least a 4.0 kernel and no existing or required

+`overlay` graph data, then `overlay2` may be used.

+

+> **Note**

+> `overlay2` graph data will not interfere with `overlay` graph data. However

+> when switching to `overlay2`, the user is responsible for removing

+> `overlay` graph data to avoid storage duplication.

 ## Related information

@@ -226,7 +226,7 @@ output otherwise.

   Force the Docker runtime to use a specific storage driver.

 **--selinux-enabled**=*true*|*false*

-  Enable selinux support. Default is false. SELinux does not presently support the overlay storage driver.

+  Enable selinux support. Default is false. SELinux does not presently support either of the overlay storage drivers.

 **--storage-opt**=[]

   Set storage driver options. See STORAGE DRIVER OPTIONS.