85 lines
3.8 KiB
Markdown
85 lines
3.8 KiB
Markdown
<!--[metadata]>
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+++
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title = "Migrate to Engine 1.10"
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description = "Migrate to Engine 1.10"
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keywords = ["docker, documentation, engine, upgrade, migration"]
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[menu.main]
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parent = "engine_use"
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weight=79
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+++
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<![end-metadata]-->
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# Migrate to Engine 1.10
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Starting from version 1.10 of Docker Engine, we completely change the way image
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data is addressed on disk. Previously, every image and layer used a randomly
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assigned UUID. In 1.10 we implemented a content addressable method using an ID,
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based on a secure hash of the image and layer data.
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The new method gives users more security, provides a built-in way to avoid ID
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collisions and guarantee data integrity after pull, push, load, or save. It also
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brings better sharing of layers by allowing many images to freely share their
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layers even if they didn’t come from the same build.
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Addressing images by their content also lets us more easily detect if something
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has already been downloaded. Because we have separated images and layers, you
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don’t have to pull the configurations for every image that was part of the
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original build chain. We also don’t need to create layers for the build
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instructions that didn’t modify the filesystem.
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Content addressability is the foundation for the new distribution features. The
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image pull and push code has been reworked to use a download/upload manager
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concept that makes pushing and pulling images much more stable and mitigate any
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parallel request issues. The download manager also brings retries on failed
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downloads and better prioritization for concurrent downloads.
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We are also introducing a new manifest format that is built on top of the
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content addressable base. It directly references the content addressable image
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configuration and layer checksums. The new manifest format also makes it
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possible for a manifest list to be used for targeting multiple
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architectures/platforms. Moving to the new manifest format will be completely
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transparent.
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## Preparing for upgrade
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To make your current images accessible to the new model we have to migrate them
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to content addressable storage. This means calculating the secure checksums for
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your current data.
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All your current images, tags and containers are automatically migrated to the
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new foundation the first time you start Docker Engine 1.10. Before loading your
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container, the daemon will calculate all needed checksums for your current data,
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and after it has completed, all your images and tags will have brand new secure
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IDs.
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**While this is simple operation, calculating SHA256 checksums for your files
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can take time if you have lots of image data.** On average you should assume
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that migrator can process data at a speed of 100MB/s. During this time your
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Docker daemon won’t be ready to respond to requests.
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## Minimizing migration time
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If you can accept this one time hit, then upgrading Docker Engine and restarting
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the daemon will transparently migrate your images. However, if you want to
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minimize the daemon’s downtime, a migration utility can be run while your old
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daemon is still running.
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This tool will find all your current images and calculate the checksums for
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them. After you upgrade and restart the daemon, the checksum data of the
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migrated images will already exist, freeing the daemon from that computation
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work. If new images appeared between the migration and the upgrade, those will
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be processed at time of upgrade to 1.10.
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[You can download the migration tool
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here.](https://github.com/docker/v1.10-migrator/releases)
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The migration tool can also be run as a Docker image. While running the migrator
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image you need to expose your Docker data directory to the container. If you use
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the default path then you would run:
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$ docker run --rm -v /var/lib/docker:/var/lib/docker docker/v1.10-migrator
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If you use the
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devicemapper storage driver, you also need to pass the flag `--privileged` to
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give the tool access to your storage devices.
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