Revert "Fix implicit DeviceMapper selection"

This reverts commit 0a376291b2213699f986a7bca1cc8c4f4ed00f8d.

Signed-off-by: David Calavera <david.calavera@gmail.com>
This commit is contained in:
David Calavera 2015-07-07 12:27:19 -07:00 committed by Tibor Vass
parent 19e5936533
commit 083daaeb2b
2 changed files with 78 additions and 0 deletions

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@ -323,6 +323,45 @@ 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
Currently supported options of `zfs`:
* `zfs.fsname`

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@ -451,6 +451,45 @@ 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