Description

I am running a CI process that builds images on a windows 2016 host Virtual Machine. A scheduled job runs every 4 hours to clear up space, but this does not seem to be reclaiming the space that docker is suggesting. The amount reclaimed has been decreasing.

Currently I have a 60Gb virtual machine that is running server core and when I run docker system prune -fa i get the following output

TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 0 0 0 B 0 B
Containers 0 0 0 B 0 B
Local Volumes 0 0 0 B 0 B

However running a scan of C:\ProgramData\docker I can see that there are many Gb's of files here, especially under windows filter. With a scan in progress, where docker is reporting zero images I currently have:

C:\ProgramData\docker - 20.5Gb - 188398 files - 66838 directories
C:\ProgramData\docker\windowsfilter - 20.4Gb - 145451 files - 66752 directories

If i run docker images and docker ps -a these are both empty.

There seems to be a gradual decline in the space that is reclaimed, like dangling images are not being detected and not picked up.

One thing to note is that I am trying to delete all images to free up space; then on my next builds I am pulling in windowsservercore or nanoserver from the build of the images, i am not explicitly pulling windowsservercore or nanoserver.

Output of docker version:

docker version
Client:
 Version:      1.13.1
 API version:  1.26
 Go version:   go1.7.5
 Git commit:   092cba3
 Built:        Wed Feb  8 08:47:51 2017
 OS/Arch:      windows/amd64

Server:
 Version:      1.13.1
 API version:  1.26 (minimum version 1.24)
 Go version:   go1.7.5
 Git commit:   092cba3
 Built:        Wed Feb  8 08:47:51 2017
 OS/Arch:      windows/amd64
 Experimental: false

Output of docker info:

docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 1.13.1
Storage Driver: windowsfilter
 Windows:
Logging Driver: json-file
Plugins:
 Volume: local
 Network: l2bridge l2tunnel nat null overlay transparent
Swarm: inactive
Default Isolation: process
Kernel Version: 10.0 14393 (14393.693.amd64fre.rs1_release.161220-1747)
Operating System: Windows Server 2016 Standard
OSType: windows
Architecture: x86_64
CPUs: 4
Total Memory: 3.997 GiB
Name: winch03
ID: 6QNU:V7HZ:D7DG:RTJH:SIQ2:BKRE:WBDD:UHBB:RIVA:3RXB:PI4R:TAX2
Docker Root Dir: C:\ProgramData\docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: -1
 Goroutines: 22
 System Time: 2017-02-22T12:04:10.5920341Z
 EventsListeners: 0
Username: xxxx
Registry: https://index.docker.io/v1/
Labels:
 hosttype=windows
 dc=ashford
 hostrole=dev
Experimental: false
Insecure Registries:
 192.168.xxx.xx:5000
 localhost:5000
 127.0.0.0/8
Live Restore Enabled: false

Running windows server 2016 on Hyper-V, fully patched with latest Windows Updates/

Expected Outcome
As I am deleting all images I would expect the amount of space reclaimed to be consistent and not reducing over time to a point where very little is reclaimed. It seems like there are dangling or orphaned images that are remaining that are not being detected.