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Questions tagged [device-mapper]

Block layer component of the Linux kernel to create and manage virtual block devices atop of physical block devices. QUESTIONS MUST BE PROGRAMMING RELATED.

69 questions
299
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11 answers

How to analyze disk usage of a Docker container

I can see that Docker takes 12GB of my filesystem: 2.7G /var/lib/docker/vfs/dir 2.7G /var/lib/docker/vfs 2.8G /var/lib/docker/devicemapper/mnt 6.3G /var/lib/docker/devicemapper/devicemapper 9.1G /var/lib/docker/devicemapper 12G …
AlonL
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10 answers

Why is docker image eating up my disk space that is not used by docker

I have setup docker and I have used completely different block device to store docker's system data: [root@blink1 /]# cat /etc/sysconfig/docker # /etc/sysconfig/docker other_args="-H tcp://0.0.0.0:9367 -H unix:///var/run/docker.sock -g…
ming.kernel
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40
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4 answers

Clean docker environment: devicemapper

I have a docker environment with 2 containers (Jenkins and Nexus, both with their own named volume). I have a daily cron-job which deletes unused containers and images. This is working fine. But the problem is inside my devicemapper: du -sh…
DenCowboy
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18
votes
5 answers

Can't run Docker container due device mapper error

I just can't create and run new containers in Docker anymore. But in the same time a can run previously created containers. When I try to do something like this: [user@host ~ ] docker run --name=fpm-5.3 debian:jessie 2014/07/12 07:34:08 Error:…
loadaverage
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9
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1 answer

How to clean docker devicemapper folder properly ?

I have some problem about the storage. The folder /var/lib/docker/devicemapper/ is taking 50% of my storage. In the folder /var/lib/docker/devicemapper/mnt, I have many empty folders. How can I properly clean docker devicemapper and remove all…
Youssouf Maiga
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7
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1 answer

Share docker images between hosts with NFS

I'building a mesosphere infrastructure on AWS instances with 3 master servers (running zookeeper, mesos-master, marathon and haproxy) and N slaves (running mesos-slave and docker). If I run the same container on different slaves marathon downloads…
sekipaolo
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7
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1 answer

How to tell Docker to use dm/LVM backend for volumes instead of vfs

I recently heard (from a RedHat guy) that "direct-LVM"(devicemapper) is the recommended storage-backend for production setups, so I wanted to try that out on a CentOS 7 VM. (where loopback-LVM seems to be the default). So I created a separate…
powo
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6
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0 answers

How do I clear a thinpool device for docker

I am running docker on a Redhat system with devicemapper and thinpool device just as recommended for production systems. Now when I want to reinstall docker I need two steps: 1) remove docker directory (in my case /area51/docker) 2) clear thinpool…
Tom
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6
votes
1 answer

create device mapper target

I am trying to implement device mapper target by referring to the already existing ones dm-linear, dm-snapshot, dm-cache etc. In my implementation, I need to perform a read/modify/write operation on a certain sector range. Since the device mapper…
Rashid Shaikh
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5
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1 answer

docker - driver "devicemapper" failed to remove root filesystem after process in container killed

I am using Docker version 17.06.0-ce on Redhat with devicemapper storage. I am launching a container running a long-running service. The master process inside the container sometimes dies for whatever reason. I get the following error message.…
bjonen
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5
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0 answers

How to mount image in docker whose storage driver is devicemapper

I wonder if I can mount an image(ex. ubuntu image) in docker whose storage driver is devicemapper "without executing it as a container". Actually I succeeded to mount the filesystem in a container like this. type "docker run -it ubuntu" type "df…
Hs Kim
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2
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2 answers

Mount LVM overlays/snapshots?

I'm trying to programmatically mount a disk image created with the Fedora LiveUSB creator, and I'm encountering some issues. From what I've been told, it's very difficult to mount LVM snapshots outside of the host system. I have both the "pristine"…
lfaraone
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2
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1 answer

docker devicemapper data file size increasing exponentially and consuming my host disk 90%

My Docker details Client: Version: 1.11.0 API version: 1.23 Go version: go1.7.1 Git commit: 4dc5990 Built: OS/Arch: linux/amd64 Server: Version: 1.11.0 API version: 1.23 Go version: go1.7.1 Git commit: 4dc5990 …
Chandan Kashyap
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1 answer

According to the union file system, does image actually container another image?

In Docker, an image is a stack of Read-only image layers. We also know that images share layers or other images. My question is about how this sharing mechanism work. Does an image have pointers to the Docker storage driver or do they actually…
ethankong113
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2
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2 answers

how `docker cp` command works

The command docker cp is used to copy files from host machine to container and vice versa. This command works even if container is in stop state or exited. Docker uses layered approach for storing images and when we run container by using this…
Yogesh Jilhawar
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