Why is the backup or copy of the graphRoot directory utilized by podman or Docker much larger than anticipated?
Issue
- When using Red Hat Enterprise Linux or Red Hat OpenShift, and utilizing a container solution such as
podman
,docker
, orcri-o
that is using theoverlayfs
driver to store container images and container data, when attempting to copy everything from thegraphRoot
directory (by default located at/var/lib/containers/storage
forpodman
andcri-o
) the backup size is much larger than the tools withinpodman
ordocker
report the combined size of container images and container data. - Why when I perform copies of this
graphRoot
directory is data duplicated, or much larger than the size reported by the tools that are using this directory?
Environment
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift 3
- Red Hat OpenShift 4
- Podman, Docker, or CRI-O using the
overlay
graph driver for storage
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