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Questions tagged [unionfs]

UnionFS is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems.

About

UnionFS is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems. It allows files and directories of separate file systems, known as branches, to be transparently overlaid, forming a single coherent file system. Contents of directories which have the same path within the merged branches will be seen together in a single merged directory, within the new, virtual filesystem.

Links

Wikipedia

Official UnionFS home page

19 questions
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multiple volumes to single target directory?

Is there a way to mount multiple volumes from a host to form a single target mount point? A bit like this: docker run --name ubuntu_bash \ --rm --interactive --tty \ --volume=/media/Large/videos:/videos \ …
Sridhar Sarnobat
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docker commit running container

When committing a running container with docker commit, is this creating a consistent snapshot of the filesystem? I'm considering this approach for backing up containers. You would just have to docker commit : and push…
Florian Gutmann
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How does Docker keep the image immutable

From the Docker documentation : The Docker image is read-only. When Docker runs a container from an image, it adds a read-write layer on top of the image (using a UnionFS) in which your application runs. How are changes reconciled across layers?…
user6317694
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Eliminating the impact of UnionFS on results when benchmarking inside Docker

I am trying to benchmark the overall system performance of running Docker using the Phoronix Test Suite 6.4.0 Milestone 2 running inside a fedora:23 image based container. One thing that must be considered is, that Docker uses a proprietary UnionFS…
Slazer
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Union mounts into Docker containers

If I have a directory d1/, I know I can mount it at /mountPoint inside a Docker container by doing this: docker run -v /path/to/d1:/mountPoint ... However, I have two directories d1/ and d2/ (let's say they contain files a.txt and b.txt…
David North
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UnionFS: How to persist changes in the overlay/upperdir into the base/lowerdir filesystem?

Suppose to have the following scenario, on a linux system: An ext4 data partition mounted as Read-Only: data_ro An overlay partition: data_overlay The two of them union-mounted using UnionFS: mount -t overlayfs -o…
feryllt
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overlayfs inside docker container

Is it possible to mount an overlay fs inside a (privileged) docker container? At least my intuitive approach, which works fine outside of a container, fails: > mkdir /tmp/{up,low,work,merged} > mount -t overlay overlay -o…
MNayer
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Does Overlayfs support upper layer to be nfs export?

Does overlayfs support having upper layer as nfs mount point? I am able to have lower layer as nfs mount point but not upper? Any workaround possible? Kernel version -> 4.4.0-21-generic Ubuntu 16.04
Vaibhav Khanduja
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How file lookup work in Docker container

According to Docker docs, every Dockerfile instruction create a layer, and all the layers are kept when you create new image based on an old one. Then when I create my own image, I might have hundreds of layers involved because of the recursive…
matrix
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Inspect docker container FS changes from host

I've started a docker container and I've modified a file. At some point later I'd like to inspect this change from the docker host. Now I use docker cp to export the file, inspect it, delete it. But this multistep copy-read-delete process seems like…
Dane O'Connor
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Give Docker access to host directory but discard changes later

I want to achieve the following with Docker: I want to give a container access to a host directory, such that the container can make changes, but the changes are discarded once the container is exiting/removed (pretty much like an overlayfs).…
Sleik
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Does file touch create a copy in the docker container layer?

What about making only a file timestamp change (i.e. touch'ed) in a docker container? Would UFS (or the varianet used) create a file copy in the docker container layer or is it able to handle this scenario more efficiently? Looking to pinpoint…
John K
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How to overlay a particular folder in one project into the same folder on other projects

I have a use case where projects A, B and C are all using a third party tool with an opinionated directory layout. Each project has some duplicated files as well as their own custom files within the same layout. To allow code reuse I would like to…
Rene Wooller
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How to mock fs module together with unionfs?

I have written a test case that successfully load files into virtual FS, and at the same time mounted a virtual volume as below describe("should work", () => { const { vol } = require("memfs"); afterEach(() => vol.reset()); beforeEach(() => { …
Isaac
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Using unionfs from inside an appimage

I'm creating an overlay FS (using unionfs-fuse) from a script in an AppImage (created with appimage-builder v0.9.2). The overlay is mounted successfully, but at the end of the script, it fails to unmount properly with 'Operation not…
Francois
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