Why is docker image eating up my disk space that i

Question

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 /disk1/docker"

Note that /disk/1 is using a completely different hard drive /dev/xvdi

Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1      7.8G  5.1G  2.6G  67% /
devtmpfs        1.9G  108K  1.9G   1% /dev
tmpfs           1.9G     0  1.9G   0% /dev/shm
/dev/xvdi        20G  5.3G   15G  27% /disk1
/dev/dm-1       9.8G  1.7G  7.6G  18% /disk1/docker/devicemapper/mnt/bb6c540bae25aaf01aedf56ff61ffed8c6ae41aa9bd06122d440c6053e3486bf
/dev/dm-2       9.8G  1.7G  7.7G  18% /disk1/docker/devicemapper/mnt/c85f756c59a5e1d260c3cdb473f3f4d9e55ac568967abe190eeaf9c4087afeac

The problem is that when I continue download docker images and run docker containers, it seems that the other hard drive /dev/xvda1 is also used up.

I can verify this problem by remove some docker images. After I removed some docker images, /dev/xvda1 has some more extra space now.

Am I missing something?

My docker version:

[root@blink1 /]# docker info
Containers: 2
Images: 42
Storage Driver: devicemapper
 Pool Name: docker-202:1-275421-pool
 Pool Blocksize: 64 Kb
 Data file: /disk1/docker/devicemapper/devicemapper/data
 Metadata file: /disk1/docker/devicemapper/devicemapper/metadata
 Data Space Used: 3054.4 Mb
 Data Space Total: 102400.0 Mb
 Metadata Space Used: 4.7 Mb
 Metadata Space Total: 2048.0 Mb
Execution Driver: native-0.2
Kernel Version: 3.14.20-20.44.amzn1.x86_64
Operating System: Amazon Linux AMI 2014.09

Answer 1

It's a kernel problem with devicemapper, which affects the RedHat family of OS (RedHat, Fedora, CentOS, and Amazon Linux). Deleted containers don't free up mapped disk space. This means that on the affected OSs you'll slowly run out of space as you start and restart containers.

The Docker project is aware of this, and the kernel is supposedly fixed in upstream (https://github.com/docker/docker/issues/3182).

A work-around of sorts is to give Docker its own volume to write to ("When Docker eats up you disk space"). This doesn't actually stop it from eating space, just from taking down other parts of your system after it does.

My solution was to uninstall docker, then delete all its files, then reinstall:

sudo yum remove docker
sudo rm -rf /var/lib/docker
sudo yum install docker

This got my space back, but it's not much different than just launching a replacement instance. I have not found a nicer solution.

Answer 2

Move the /var/llib/docker directory.

Assuming the /root directory has enough room, if not, substitute for one that does,

sudo systemctl stop docker

mv /usr/lib/docker /root


ln -s /root/docker /var/lib/docker

systemctl start docker

In this way, you don't have to reconfigure docker.

Answer 3

Yes, Docker use /var/lib/docker folder to store the layers. There are ways to reclaim the space and move the storage to some other directory.

You can mount a bigger disk space and move the content of /var/lib/docker to the new mount location and make sym link.

There is detail explanation on how to do above task.

http://www.scmtechblog.net/2016/06/clean-up-docker-images-from-local-to.html

You can remove the intermediate layers too.

https://github.com/vishalvsh1/docker-image-cleanup

Answer 4

I had a similar problem and I think this happens when you don't have enough space in the disk for all your docker images. I had 6GB reserved for docker images which it turned out not to be enough in my case. Anyway, I had removed every image and container and still disk looked full. Most of the space was being used by /var/lib/docker/devicemapper and /var/lib/docker/tmp.

This command didn't work for me:

# docker ps -qa | xargs docker inspect --format='{{ .State.Pid }}' | xargs -IZ fstrim /proc/Z/root/

First, I stopped docker service:

sudo service docker stop

Then I deleted /var/lib/docker:

Then I did what somebody suggested here in https://github.com/docker/docker/issues/18867#issuecomment-232301073

• Remove existing instance of docker metadata rm -rf /var/lib/docker

  sudo rm -rf /var/lib/docker

• Pass following options to docker daemon: -s devicemapper --storage-opt dm.fs=xfs --storage-opt dm.mountopt=discard

• Start docker daemon.

For last two steps, I run:

sudo dockerd -s devicemapper --storage-opt dm.fs=xfs --storage-opt dm.mountopt=discard

Answer 5

Deleting my entire /var/lib/docker is not ok for me. These are a safer ways:

Solution 1:

The following commands from the issue clear up space for me and it's a lot safer than deleting /var/lib/docker or for Windows check your disk image location here.

Before:

> docker info
Metadata file: 
Data Space Used: 53.38 GB
Data Space Total: 53.39 GB
Data Space Available: 8.389 MB
Metadata Space Used: 6.234 MB
Metadata Space Total: 54.53 MB
Metadata Space Available: 48.29 MB

Command in newer versions of Docker e.g. 17.x +

> docker system prune -a

(It will show the 'Total reclaimed space')

e.g. Total reclaimed space: 1.243GB

Solution 2:

Along with this, make sure your programs inside the docker container are not writing many/huge files to the file system.

Check your running docker process's space usage size

docker ps -s #may take minutes to return

or for all containers, even exited

docker ps -as #may take minutes to return

You can then delete the offending container/s

docker rm <CONTAINER ID>

Find the possible culprit which may be using gigs of space

docker exec -it <CONTAINER ID> "/bin/sh"
du -h

In my case the program was writing gigs of temp files.

(Nathaniel Waisbrot mentioned in the accepted answer this issue and I got some info from the issue)

---

OR

Commands in older versions of Docker e.g. 1.13.x (run as root not sudo):

# Delete 'exited' containers
docker rm -v $(docker ps -a -q -f status=exited)

# Delete 'dangling' images (If there are no images you will get a docker: "rmi" requires a minimum of 1 argument)
docker rmi $(docker images -f "dangling=true" -q)

# Delete 'dangling' volumes (If there are no images you will get a docker: "volume rm" requires a minimum of 1 argument)
docker volume rm $(docker volume ls -qf dangling=true)

After :

> docker info
Metadata file: 
Data Space Used: 1.43 GB
Data Space Total: 53.39 GB
Data Space Available: 51.96 GB
Metadata Space Used: 577.5 kB
Metadata Space Total: 54.53 MB
Metadata Space Available: 53.95 MB

Answer 6

As mentioned in issue #18867 - Delete data in a container devicemapper can not free used space from Github.com

Try running the below command:

# docker ps -qa | xargs docker inspect --format='{{ .State.Pid }}' | xargs -IZ fstrim /proc/Z/root/

It uses the fstrim tool to trim the devicemapper thinly-provisioned disk.