From 1028f69f59c0cf398bf0833b239be3061c0a4e16 Mon Sep 17 00:00:00 2001 From: David Calavera Date: Tue, 30 Jun 2015 09:00:02 -0700 Subject: [PATCH] Fix implicit DeviceMapper selection DeviceMapper must be explicitly selected because the Docker binary might not be linked to the right devmapper library. With this change, Docker fails fast if the driver detection finds the devicemapper directory but the driver is not the default option. The option `override_udev_sync_check` doesn't make sense anymore, since the user must be explicit to select devicemapper, so it's being removed. Docker fails to use devicemapper only if Docker has been built statically unless the option was explicit. Signed-off-by: David Calavera --- docs/reference/commandline/daemon.md | 36 ------------------------- man/docker.1.md | 39 ---------------------------- 2 files changed, 75 deletions(-) diff --git a/docs/reference/commandline/daemon.md b/docs/reference/commandline/daemon.md index 0cd9f734e0..cb56ab5454 100644 --- a/docs/reference/commandline/daemon.md +++ b/docs/reference/commandline/daemon.md @@ -323,42 +323,6 @@ options for `zfs` start with `zfs`. $ docker -d --storage-opt dm.blkdiscard=false - * `dm.override_udev_sync_check` - - Overrides the `udev` synchronization checks between `devicemapper` and `udev`. - `udev` is the device manager for the Linux kernel. - - To view the `udev` sync support of a Docker daemon that is using the - `devicemapper` driver, run: - - $ docker info - [...] - Udev Sync Supported: true - [...] - - When `udev` sync support is `true`, then `devicemapper` and udev can - coordinate the activation and deactivation of devices for containers. - - When `udev` sync support is `false`, a race condition occurs between - the`devicemapper` and `udev` during create and cleanup. The race condition - results in errors and failures. (For information on these failures, see - [docker#4036](https://github.com/docker/docker/issues/4036)) - - To allow the `docker` daemon to start, regardless of `udev` sync not being - supported, set `dm.override_udev_sync_check` to true: - - $ docker -d --storage-opt dm.override_udev_sync_check=true - - When this value is `true`, the `devicemapper` continues and simply warns - you the errors are happening. - - > **Note:** - > The ideal is to pursue a `docker` daemon and environment that does - > support synchronizing with `udev`. For further discussion on this - > topic, see [docker#4036](https://github.com/docker/docker/issues/4036). - > Otherwise, set this flag for migrating existing Docker daemons to - > a daemon with a supported environment. - ## Docker execdriver option diff --git a/man/docker.1.md b/man/docker.1.md index 98135e50ff..ee0344a14f 100644 --- a/man/docker.1.md +++ b/man/docker.1.md @@ -451,45 +451,6 @@ removed. Example use: `docker -d --storage-opt dm.blkdiscard=false` -#### dm.override_udev_sync_check - -By default, the devicemapper backend attempts to synchronize with the -`udev` device manager for the Linux kernel. This option allows -disabling that synchronization, to continue even though the -configuration may be buggy. - -To view the `udev` sync support of a Docker daemon that is using the -`devicemapper` driver, run: - - $ docker info - [...] - Udev Sync Supported: true - [...] - -When `udev` sync support is `true`, then `devicemapper` and `udev` can -coordinate the activation and deactivation of devices for containers. - -When `udev` sync support is `false`, a race condition occurs between -the`devicemapper` and `udev` during create and cleanup. The race -condition results in errors and failures. (For information on these -failures, see -[docker#4036](https://github.com/docker/docker/issues/4036)) - -To allow the `docker` daemon to start, regardless of whether `udev` sync is -`false`, set `dm.override_udev_sync_check` to true: - - $ docker -d --storage-opt dm.override_udev_sync_check=true - -When this value is `true`, the driver continues and simply warns you -the errors are happening. - -**Note**: The ideal is to pursue a `docker` daemon and environment -that does support synchronizing with `udev`. For further discussion on -this topic, see -[docker#4036](https://github.com/docker/docker/issues/4036). -Otherwise, set this flag for migrating existing Docker daemons to a -daemon with a supported environment. - # EXEC DRIVER OPTIONS Use the **--exec-opt** flags to specify options to the exec-driver. The only