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

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

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

Example output:

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 you a warning that it will remove all the stopped containers,networks, images and build cache. Generally it's safe to remove this. (Next time you run a container it may pull from the Docker registry)

Example output:

Total reclaimed space: 1.243GB

You can then run docker info again to see what has been cleaned up

docker info

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