I'm new to Docker and trying to evaluate methods and processes for doing backups on a CentOS host and container. From reading numerous articles about Docker backups, I've come to the following conclusions:

  1. No one does block-level backups of Docker volumes, only file-level.
  2. The backup process can run from the host or from a backup container, but if run from a container has no way to access underlying devices (by definition of containers).

I completely understand the second point, but is (or why is) it not possible to get consistent block-level backups from a volume? I would think that a volume backed by LVM could be snapshotted from the host and backed up appropriately.

  • A docker volume is a directory on the host. – Brian Jan 9 '15 at 15:19
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    No one does block-level backups on Ubuntu because Docker on Ubuntu uses AUFS. Other distributions don't have this problem. – Michael Hampton Jan 9 '15 at 15:27
  • I updated the question to specify that I'm running a CentOS host and container. However, on Ubuntu I believe only containers are backed by AUFS and not volumes-- they are simply directories on the host that are accessible in the container. This would suggest that even on Ubuntu a volume could reside in a directory backed by LVM or even btrfs and could be backed up at the block level. – Chris Mendez Jan 9 '15 at 21:42

You should checkout ClusterHQ's Flocker, it leverages ZFS snapshot replication over the network.

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