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@@ -28,7 +28,12 @@ persistent or shared data:
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- Data volumes can be shared and reused between containers
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- Changes to a data volume are made directly
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- Changes to a data volume will not be included when you update an image
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-- Volumes persist until no containers use them
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+- Data volumes persist even if the container itself is deleted
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+
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+Data volumes are designed to persist data, independent of the container's life
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+cycle. Docker will therefore *never* automatically delete volumes when you remove
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+a container, nor will it "garbage collect" volumes that are no longer referenced
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+by a container.
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### Adding a data volume
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@@ -141,6 +146,14 @@ be deleted. To delete the volume from disk, you must explicitly call
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`docker rm -v` against the last container with a reference to the volume. This
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allows you to upgrade, or effectively migrate data volumes between containers.
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+> **Note:** Docker will not warn you when removing a container *without*
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+> providing the `-v` option to delete its volumes. If you remove containers
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+> without using the `-v` option, you may end up with "dangling" volumes;
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+> volumes that are no longer referenced by a container.
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+> Dangling volumes are difficult to get rid of and can take up a large amount
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+> of disk space. We're working on improving volume management and you can check
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+> progress on this in [pull request #8484](https://github.com/docker/docker/pull/8484)
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+
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## Backup, restore, or migrate data volumes
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Another useful function we can perform with volumes is use them for
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James Turnbull