Qcow2 image maintenance

[sivel (Matt Martz)]

Expected behavior

The Docker.qcow2 image on my system has grown to over 30GB at the moment.

I tend to keep my downloaded Docker images to a minimum, as I am using a 256GB SSD, and am concerned about disk utilization.

It would be beneficial to have a way to have forced or routine maintenance on that image to shrink the disk utilization.

Actual behavior

Information

OS X: version 10.11.2 (build: 15C50)
Docker.app: version v1.11.1-beta12
Running diagnostic tests:
[OK]      Moby booted
[OK]      driver.amd64-linux
[OK]      vmnetd
[OK]      osxfs
[OK]      db
[OK]      slirp
[OK]      menubar
[OK]      environment
[OK]      Docker
[OK]      VT-x
Docker logs are being collected into /tmp/20160519-093925.tar.gz
Most specific failure is: No error was detected
Your unique id is: C57F9862-9CD4-4AF5-9AE8-8D498F28F15A
Please quote this in all correspondence.

Steps to reproduce the behavior

1. docker pull a bunch of images
2. Watch Docker.qcow2 grow

[aleveille (Alexandre)]

The situation you are facing seems to be the same as the one described in these threads:

Where does Docker keep images/containers so i can better track my disk usage

Expected behavior Some setting describing where on my host I can see location of resources used by the application - like Images, Containers. Give me an idea what/where they are using on Disk. Actual behavior While there are artifacts here Library/Containers/com.docker.docker - there is no explanation of what is what and quite frankly, would like to understand why Docker.qcow2 is 16Gb - yet I have no Images loaded or containers. We run Macs with SSD’s and disk space is expensive or non-existen…

Consistently out of disk space in docker beta

Expected behavior The docker for mac beta uses all available disk space on the host until there is no more physical disk space available. Actual behavior Docker builds fail with: no space left on device when building an image that has a lot of debian deps. Information There is ~190GB of disk space available left on this machine. OS X: version 10.11.3 (build: 15D21) Docker.app: version v1.11.0-beta7 Running diagnostic tests: [OK] docker-cli [OK] Moby booted [OK] driver.amd6…

HTH,
Alexandre

[cameronbrunner]

To lessen the impact of an out of control qcow2 file I have placed my in a loopback disk on my mac that has a fixed size.

What I did was create a new disk image using Mac’s Disk Utility and set its size to a value that I felt would be reasonable given my use case (20G). After shutting down Docker for Mac and removing my old qcow2 file (it was bigger than 20G) I then mounted that disk image and linked my disk image to the Docker for Mac qcow2 HD location:

ln -s /Volumes/docker-for-mac\ loopback/hd.qcow2 \
~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/Docker.qcow2 

Now docker for Mac is writing into my disk image. I imagine I will run into a docker failure once the image fills up but at that point intend on doing one of the qcow2 cleanup commands as I should have plenty of space to make a copy of my image.