Docker size questions

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Hi, lately i struggle a little with size of docker image


some time ago i raised the size to 25 gigs to make sure im fine, but lately i pretty often see the size grows (warning 75 % utilization) and shrinks again,

so my best bet is plex is the issue due its pretty sure then happening when a remote stream is playing and transcode is in progress.


but what wonders me when i want to look where the issue is, when i check container size from docker tab i get as sample this result



which shows me now 10.4 gigs in use, so i wonder why 10.4 GB from 25 should result in 71 %



so to "search" for a error here (like wrong path etc) ... makes it a little complicated in my terms ...


even in addition (Container + writeable) doesnt fit ...


so, question is, to simple debug docker size, is there a alternative, better way ? or really still best bet to uninstall/reinstall docker by docker to see where it changes ?


for any tipps, thanks ahead.

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So the listed container sizes only apply to the containers that are there, but the docker image itself can have left over stuff from previous dockers you've installed and deleted also.  That could be one thing to look at.


For Plex, you should have a transcoding location mapped to the array somewhere so that it's not "in" your docker container.  By default anything that's not mapped to the array ends up in your docker file taking up space.


You can read a few things about mapping docker containers and why the docker image fills up here


You can also use a couple apps such as Portainer to examine your docker containers and see what's taking up space...


One thing I do occasionally is use the information from these comments to clean up my residual docker containers


I start all my docker containers that I have installed / want to keep / not be touched and open a console window and run 'docker system prune' to remove any left over stuff from old dockers I've deleted.



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out of fun now i deleted all my dockers, also checked i have no orphaned docker images left ...


this is my docker tap in advanced mode (show orphan images)




its completely empty as expected, now i waited a while so docker size can update ...


now, in docker tab checking container size




as expected, now checking unraid, still says 30 % filled ...




now taking a look at docker settings




whatever these used 6.5 GB are ... they dont come from the dockers or pathes ... are there always kept "leftovers" when doing something new ... ? idk


but like this its hard to understand if there is may something wrong or not ...


scrub, prune, etc ... wont free up the space, so i ll redo my docker image now to get a "real" result in my terms, but this is what i wanted to point at,

there is sometimes something wrong in the docker image which ends in wrong results or "costing" time due searching for docker setup errors.

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  • 1 month later...

@limetech i would like to ask again if there is may something wrong or to debug


from July 14 to today, my docker image is filling up slowly again "in the background" like described here


when i look today again, i renewed the image on 14th July with a 30 GB image, its stated now as 66 % filled again (was like 35 when i started)


my personal guess, after each update there are leftovers somewhere in the docker image ...


current state now







im pretty sure, when i just delete all dockers now i would be left with some GB usage in the docker.img ... even with no dockers left installed,

is there a way to check what is inside the docker image and may could cause this behaviour ?

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14 hours ago, dukiethecorgi said:

I recently installed the Portainer container, and I noticed that Docker was showing over 400 volumes.


From the unraid console I ran

docker volume prune 

to remove the unused volumes and my docker volume reduced in size 38gb.

thanks, that also freed up 4GB here and i come back again to where it should be


@limetech normal behaviour ?

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