Questions tagged [overlayfs]

For questions concerning the Overlay Filesystem, which was included in Linux kernel 3.18.

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Protocol Error using Overlay FS with VirtualBox shared folders

I have a VirtualBox VM running Xenial. I want to share some folders with my host OS, but use the native filesystem for build artifacts due to running MySQL with InnoDB and some config I cannot change ...
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21 views

Does /etc/fstab overwrite mounts done during initramfs

I am experimenting with an Archlinux VM and two virtual disks. I am trying to mount / as an OverlayFS with, for example: sda1 containng the lowerdir and sdb1 containing the upperdir and the workdir. ...
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1answer
38 views

How can I use OverlayFS to “combine” multiple storage into one? Is this possible?

I've been looking into using OverlayFS. I'd like to be able to combine a bunch of already formatted, already containing data, hard drives. All hard drives are formatted with ext4. The goal is to ...
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115 views

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 ...
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How do I remount / on my live CD to include /mnt/sda1/overlaytest as upperdir?

How do I remount / on my live CD to include /mnt/sda1/overlaytest as upperdir? I tried: { mountpoint /mnt/sda1 && sudo mkdir /mnt/sda1/overlaytest && mount -v -o remount -t ...
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1answer
89 views

Overlayfs over archivemount

I am trying to apply an overlay using overlayfs over a filesystem mounted with archivemount: mkdir -p {upper,work,mount} tar zcf somefile upper/ work/ mount/ mkdir tmp archivemount -o allow_root -o ...
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2answers
48 views

Overlayfs inside archivemount

I am trying to mount an overlayfs inside an archivemount (as a follow-up to Layered or Virtual filesystem on Linux). I am doing this: mkdir -p {upper,work,mount} tar zcf somefile upper/ work/ mount/ ...
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231 views

What are the consequences of specifying same directory overlay upper/workdir and merged?

I wanted to have a simple RO overlay of my root for use in my container, but for whatever reason it didn't work: $ sudo mount -t overlay overlay -o lowerdir=/ /var/lib/machines/test/ mount: /var/lib/...
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170 views

Why overlayfs increases boot time?

Recently, I started using overlay filesystem. I'm using initram script (init=/sbin/myint) as described in Raspberry blog - raspberry overlay, yet, I noticed that it increases boot time significantly (...
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193 views

Overlayfs mounted, but get “read-only file system” on any write

I try a simple overlay example by mounting: sudo mount -t overlay -o lowerdir=/tmp/lower,upperdir=/tmp/upper/upper, workdir=/tmp/upper/workdir none /tmp/overlay (I run the full script from example ...
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431 views

Modify Ubuntu overlayroot @ boot time

The overlayroot package for Ubuntu is great, it really simplifies using overlayfs to protect the root volume from writes. I am trying to mirror what I've been doing previously and cannot seem to do ...
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121 views

(user error) OverlayFS - files deleted in current merged dir (mountpoint) reappear when merged dir remounted as lower

On Debian Stretch (running as root) this the current behaviour: # Create base directory mkdir base touch base/example # Create merge, upper and work directories for 2 layers mkdir layer1 layer1....
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2k views

using overlay2 on CentOS 7.4

How do I install and enable the overlay2 storage driver on CentOS 7? I have done many google searches on this and I see that version 7.4 is required. So I typed the following commands to confirm ...
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1answer
79 views

Apache does not see files under overlay mount

have mounted overlay fs: overlay on /srv/www/site type overlay (rw,relatime,lowerdir=/srv/www/site_orig,upperdir=/srv/www/site_custom,workdir=/srv/www/overlay_workdir) I can see and edit files under ...
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2answers
1k views

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 ...
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1answer
2k views

Mount root as overlayfs

I've been trying mount root (/) as overlayfs. OS is booting over NFS to RAM. I've added a premount script in initrd, which creates the 'work', 'upper' and 'lower' directories. During the boot ...
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613 views

Can not mount overlayfs inside initrd

I am trying to use read-only overlayfs(no workdir and upperdir) inside custom initrd. This works fine in completely booted OS: mkdir /tmp/ovl1 /tmp/ovl2 /tmp/merged mount -t overlay none -o lowerdir=...
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381 views

OverlayFS over read only rootfs fail

I need to keep one system as much intact as possible. Only soldering of HW stuff is allowed :-). I need to install a test software package and this package must not stay there in the future. I have a ...
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3answers
3k views

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 (...
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2answers
109 views

Does overlayfs redirect opened files automatically on the fly?

or I should close file - then mount overlay - and then re-open file again? i.e. #!/bin/bash my_background_process >log.txt & ... pkill my_background_process mount overlay my_background_process ...
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1answer
4k views

Unionfs vs Aufs vs Overlayfs vs mhddfs, which one do I use

I have randomly been reading about union file system which enables a user to mount multiple filesystems on top of one another simultaneously. However, am finding trouble deciding on which one to use(...
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782 views

Why can't /proc be a layer of a overlay file system (overlayfs) on linux?

Run the following commands on linux (4.4.59 and 4.9.8 are tested) and it will fail: mkdir -p /tmp/proc mount -t overlay overlay -o lowerdir=/proc:/tmp/proc /tmp/proc and there is a error message in ...
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121 views

Proper way to create “persistent” RAM fs

I'm going to reduce SSD writes, so I'd like to keep changes to some directories (like /var/log or browser cache) in memory and syncing to permanent storage periodically. I should reduce memory size as ...
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443 views

Limit the size of tmpfs with overlayroot

Recently I found out that it's possible to use overlayroot with tmpfs to create stateless readonly root. However I couldn't find any info about limiting the size of tmpfs. Is it possible?
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287 views

Fedora 25 Live Persistent Overlay Not Working

I have just created a fresh Fedora 25 Xfce 32-bit Live USB using the following command: livecd-iso-to-disk --noverify --reset-mbr --format --msdos \ --overlay-size-mb 1024 --home-size-mb 512 --...
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1answer
538 views

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 ...
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1answer
509 views

Can overlayFS support more than two layers?

As far as i read documentation the overlayFS supports two layers - upper and lower. But is there possibility to increase it to three layers?
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1answer
1k views

mounting /var as overlayfs

I'm running a read only filesystem on a raspberry pi so far everything works fine until i tried to mount /var as overlayfs for nginx and other services to work using this: VAROVRL="-o lowerdir=/var,...
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1answer
1k views

OverlayFS Seamlessly Edit File in Lower Directory

I'm trying to set up a PXEboot environment in which the base system (served over NFS to the PXE clients) is read only, and the root filesystem is an overlayfs filesystem with the read-only NFS base ...
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0answers
693 views

creating an overlay directly over a mount (systemd-fstab-generator causes error)

I would like to create an overlay over my /var directory. I am using debian/stretch with a recent kernel and install. systemd 232. I am using something along the lines of (all lines with an implied ...
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1answer
856 views

Why is my overlayfs command not working?

The commands below should be creating a root overlay, such that any modifications to root will appear in /tmp/upper However as you can see it does not appear to be working. Can anyone suggest what I ...
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1answer
1k views

Docker and OverlayFS

I'm trying to learn about docker and the overlayFS, as suggest by the official website, I installed the last kernel: 4.8.11-1.el7.elrepo.x86_64 and as suggest by them to ensure that overlay is good ...
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2answers
9k views

Linux Filesystem Overlay - what is workdir used for? (OverlayFS)

OverlayFS has a workdir option, beside two other directories lowerdir and upperdir, which needs to be an empty directory. Unfortunately the kernel documentation of overlayfs does not talk much about ...
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2answers
9k views

How to use OverlayFS to protect the root filesystem?

How do I correctly use OverlayFS to protect my root filesystem? I have an embedded system that boots and runs from an SD card. Since it will experience sudden power loss, I want to protect the root ...
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1answer
378 views

linux - OOM / swap not being used

I am getting Out of Memory errors while my swap isn't touched. I have 4GB of ram and 4GB of swap space. I enabled the swap via swapon and when doing free, I see the swap listed there. I'm thinking ...
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840 views

Is there anyway to modify one file and sync to the lower directory in OverlayFs?

I know about the overlayfs that it treats lower directory as a read-only and copy_up when we want to modify the lower file so is there any way to modify the lower file and it can copy the modified ...
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1answer
195 views

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'...
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1answer
945 views

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/...
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1answer
3k views

How can I delete changes from an overlay fs?

I have an embedded device running BusyBox, there are a number of directories mounted with overlayfs with work and data directories mounted on separate UBI partitions using the following style of ...
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342 views

How to reflect changes made to original LXC container on overlayFS snapshots?

In order to make updates easier and limit there size, I created a base LXC container, let's say c1, where i installed and configure a few default packages (using apt) which are common to all my ...
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1answer
464 views

Mounting Overlayfs in a user namespace

Is it possible to mount an Overlayfs filesystem as an unprivileged user in a user namespace in Linux kernels >4.3.3; it seems that the fix to this vulnerability has blocked this functionality entirely....
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2answers
1k views

what occupy space at overlayfs

I have a linux with a read only root filesystem and a read-write overlayfs mounted over it: # mount overlayfs on / type overlayfs (rw,relatime,lowerdir=/root_ro/,upperdir=/root_rw/) ... The ...
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1answer
258 views

Mount a large squashfs in a way that allows random writes (to a separate filesystem)?

I just received a few-dozen-gigabyte squashfs that contains a PostgreSQL database. In order to be able to conveniently query it, I need to have a write access, which makes it complicated. Is there a ...
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1answer
2k views

Merge two NFS shares with OverlayFS

I have two directories (a and b), which are NFS shares with files foo.txt and bar.txt: I want merge this two directories to directory merge (does not have to be writable) this is possible by command:...
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overlayfs: missing 'workdir' on CloneZilla start

I would clone my partition /dev/sda1 on Ubuntu 14.04. I've downloaded Clonezilla in order to clone this partition and be able to reinstall it later. As recommended on the CloneZilla's website, I used ...
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140 views

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 ...
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1answer
2k views

How to modify a lower file through an OverlayFS directory?

I want Linux's OverlayFS to behave like AUFS when writing to a lower file. I want it to write through to the lower directory. For example, I have two files named L/lower and U/upper. mount -t ...
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305 views

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 ...
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2answers
4k views

OverlayFS doesn't work with unprivileged user namespace

OverlayFS mount works weird when accessed from within the unprivileged user namespace. Best to be explained in example: ~# uname -a Linux host 4.1.0-1-amd64 #1 SMP Debian 4.1.3-1 (2015-08-03) x86_64 ...
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91 views

Light file copy with diff

Is there a way to copy a file by creating another instance of it, that is not created as a hard copy, but by a link with the difference that any edit to that file will be saved in an diff file? I ...