Questions tagged [union-mount]

A union mount creates an overlay of several filesystems on one mount point

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How to instruct systemd to use a specific unionfs for /home

Context: Say I have two workplaces. Currently, I carry a laptop along, and have external HDs staying in these workplaces to hold backups. Now, I'm given the opportunity to have a desktop in both ...
L. Levrel's user avatar
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Overlayfs as a solution to copying central file systems everywhere. In what way?

I have searched the whole internet and have watched my lecture multiple times just to understand one thing: I still can't quite understand, how is overlayFS a solution to copying the central FS for ...
Sara's user avatar
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How to appropriately set spindown (Power Management) when using SnapRaid?

I run openmediavault 4.1 and changed from RAID6 to SnapRaid with 7 hard drives for data plus parity. I remember reading installation advice on RAID setup that said "never set spindown for HDD&...
bomben's user avatar
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Using unionfs or similar as root file system in Linux?

After building Linux From Scratch several times I realized that package management is really a hard thing to do. After thinking for some time, I came across an idea. My idea is to install all packages ...
Akib Azmain Turja's user avatar
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Does remounting after changes to overlayfs underlying filesystem (UB) necessarily restore consistency?

The overlayfs documentation states that "if the underlying filesystem is changed, the behavior of the overlay is undefined, though it will not result in a crash or deadlock." And, indeed, I'...
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How to create a union mount (bind two or more directories to one mountpoint) on illumos / solaris?

I have been using union mounts, such as unionfs on FreeBSD or mergerfs on Linux, and now I would need to do the same on illumos (SmartOS). Reading illumos or SmartOS man pages is not helpful. Same ...
gsl's user avatar
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Overlay : filesystem not supported on lowerdir

I tried to mount an external storage device (a usb flash drive) with overlay (as the lowerdir the usb and as upper a temporary ramdisk) mkdir /data mkdir /data/lower mkdir /data/rw mkdir /data/root ...
Ben W's user avatar
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FUSE overlay mount with colon in path

Is it possible to do an overlay mount when one of the paths has a colon in it? All of the FUSE overlay mounting solutions I've looked at use a colon to separate the paths in the overlay, and I can't ...
AndrolGenhald's user avatar
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2 answers
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How safe is it to use unionfs in FreeBSD?

From man mount_unionfs: BUGS: THIS FILE SYSTEM TYPE IS NOT YET FULLY SUPPORTED (READ: IT DOESN'T WORK) AND USING IT MAY, IN FACT, DESTROY DATA ON YOUR SYSTEM. USE AT YOUR OWN RISK. BEWARE OF DOG. ...
Stilez's user avatar
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How to use loopback to access the lower files of a unionfs, in FreeBSD?

From man mount_unionfs: If a file exists in the upper layer then there is no way to access a file with the same name in the lower layer. If necessary, a combination of loopback and union mounts can ...
Stilez's user avatar
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Mount /var/logs as tmpfs, with help of overlayfs to save changes sometimes

Instead of just mounting tmpfs on /var/log I want to use overlayfs. /var/log are writable tmpfs, but containing files were there before tmpfs mount. This old files are not in memory of tmpfs but in ...
LeonidMew's user avatar
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22 votes
5 answers
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Merge changes to upper filesystem to lower filesystem in Linux Overlay (OverlayFS) mount

I would like to be able to merge changes from the upper filesystem of an overlay mount to a lower filesystem. I am interested both online (i.e. merge while the overlay is mounted) and offline (...
ejm's user avatar
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6 votes
1 answer
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Union mount options in Fedora

I've grown up a Debian/Ubuntu guy and I'm learning Fedora by trying to recreate the services my Ubuntu trusty box currently provides. However, I'm trying to recreate a union mount and don't see any ...
Rob D.'s user avatar
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Why mounting overlayfs with root as lowerdir produce an empty /proc in mergedir?

Here's the test case: #!/bin/bash more="$@" saved="$EUID" if [ "$EUID" = "0" ]; then echo "don't run as root" exit fi m="/tmp/mount-point" exec sudo unshare -m /bin/bash <<UNSHARED ...
Raitis Veinbahs's user avatar
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1 answer
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Mount unionfs (or aufs) branches fed from stdin?

Is it possible to feed the branch paths from stdin to the mount (or mount_unionfs) command, instead of supplying them as arguments or from a file? cat ~/dirs_with_photos.txt | mount -t unionfs I don'...
Sridhar Sarnobat's user avatar
6 votes
1 answer
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Can I use a read-write root filesystem disk image as an OverlayFS upperdir?

Is it possible to union-mount an existing disk image containing a root filesystem to the upperdir of an overlayfs mount for read-write access? I'm trying to union-mount some old disk images to a /tmp/...
codewithmichael's user avatar
2 votes
1 answer
2k views

How can I create an union merging / and another directory, on / itself?

Say, we initially have / with the following contents: /bin/foo /usr/bin/bar /usr/lib/libfoo.so We also have another directory, say /stuff, with the contents: usr/lib/mystuff/mystuff.so etc/foo/qux/...
user avatar
15 votes
1 answer
8k views

Union mount on Linux

A union mount presents a combined view of multiple directories (branches) in a single hierarchy. Ok, but how do I use one in practice, and which one? Many union mount technologies are available on a ...
Gilles 'SO- stop being evil''s user avatar
3 votes
1 answer
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overlay-filesystem that can differentiate between metadata and file content?

AFAIK with aufs when a file is touched (ie. only it's metadata changed, not it's contents), then the copy-on-write mechanism of the file system will copy the whole file into the r/w layer, essentially ...
Udo G's user avatar
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5 votes
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OverlayFS: Is mounting /foo/lower:/foo/upper to /foo safe?

Consider the following union mount: mount -t overlay -o lowerdir=/.pre-foo/lower,upperdir=/.pre-foo/upper,workdir=/.pre-foo/work overlay /foo I would like to obfuscate that /.pre-foo to minimize the ...
Laércio de Sousa's user avatar
2 votes
1 answer
967 views

Making aufs union mounts read-write

So I've got two systems, lucyvanpelt and schroeder. lucyvanpelt's /home is exported read-write to schroeder via NFS. Its location on schroeder is /mnt/home/lucyvanpelt I want to union-mount it with ...
Steely Dan's user avatar
3 votes
1 answer
5k views

SquashFS+UnionFS as root filesystem?

What's an easy way to to use a union filesystem (read-only SquashFS + R/W overlay) as /? I'm thinking of using a custom boot script as the kernel init= argument. The script would mount the SquashFS + ...
Anul's user avatar
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7 votes
3 answers
13k views

Mount directory onto root

I have a folder containing certain files. Is there a way to mount it onto /, so that the contents of a given directory appear in the corresponding locations in /? In my case, the directories contain ...
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