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I've been tasked with working with the CentOS Atomic Host distribution which comes preinstalled with Docker. My problem is I can pull from a host registry without a problem (but I don't know where it's stored), but what I'd really like to do is just scp/sftp an image over to my client PC and "docker load" the image.

If I choose auto installation, I get a "cah-docker--pool_tdata" that's 48.9 and a "cah-docker--pool_tmeta" and the /dev/mapper/cash-root is only 3 GB which can't hold an image.

Where should I be transferring the files to and could anyone give me a rundown on why these partitions are like this? I couldn't find anything in the docs about it.

user3000724
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  • Don't try to copy the files themselves, that won't work. Try to [save/load the image](http://stackoverflow.com/questions/23935141/how-to-copy-docker-images-from-one-host-to-another-without-via-repository) instead. – morxa Mar 01 '16 at 00:58
  • Right, I save the image, and then want to sftp the file over to load. The problem is I don't understand the partitions. The root partition is only 3 GB and my image is 2.5 GB so it doesn't fit there, I need it on one of the 48.9 GB partitions but don't know how to put files there. How can I put the files on the spacious partitions? – user3000724 Mar 01 '16 at 12:53

1 Answers1

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Atomic Host's only purpose is to run Docker. From the Project Atomic website:

Atomic Host is a lightweight, immutable platform, designed with the sole purpose of running containerized applications.

The only place where such a host needs a lot of disk space is the Docker pool. Therefore, the installer gives the pool as much disk space as possible and keeps the rest of the partitions very small.

To solve your problem, try to pipe the output of docker save directly into docker load. From the host where you want to copy the image from:

docker save <image> | ssh <target_host> 'docker load'

This can be improved by following this answer by kolypto:

docker save <image> | bzip2 | pv | \
 ssh <target_host> 'bunzip2 | docker load'
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morxa
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