Why are there multiple copies of docker.img?

[unburt]

I'm a new user just getting started with unraid (6.8.3). I'm having a little trouble understanding how the /system/docker/docker.img file is used. Why does it look like I have 3 separate copies of this?

 

I started my array a week ago with 1 data disk and it had a 21.5GB docker.img file on it. Now that I've added a second data disk and a cache disk, it looks like they all have separate 21.5GB docker.img files on them. Does this make sense? It looks this way to me because /mnt/disk1/system/docker/docker.img, /mnt/disk2/system/docker/docker.img, and /mnt/cache/system/docker/docker.img have three different Last Modified times. I see that the "system" share is set to use all disks but I'm not sure how that plays into here.

 

I could have sworn at the beginning I created a docker container for plex and then it disappeared after adding the new disks. Perhaps I'm hallucinating but if there are 3 different docker.img files then maybe it is looking at the wrong one?

 

I'd be happy to read documentation explaining this but I did not find what I was looking for in this section https://wiki.unraid.net/UnRAID_Manual_6#Using_Docker

 

Thanks

[trurl]

It only uses one docker image, preferably on cache. Since you added cache after enabling dockers it got created on the array first. Don't know how you got 3 though and probably not worth finding out. 

 

Go to Tools-Diagnostics and attach the complete Diagnostics ZIP file to your NEXT post. 

[unburt]

I see, I guess that's the tricky thing with files autocreated and managed by software. 

 

In further reading, I've seen some advice suggesting using the explicit disk path (mnt/cache/...) rather than the user path (

/mnt/user/system/docker/docker.img) to the docker img file. I suppose what's happened is that the user path is pointing to one of my new docker.img files and that's why my plex container "disappeared".

...

Actually, I checked just now and yes, the /mnt/user/system/docker/docker.img is the new one that's on the cache disk.

tower-diagnostics-20200601-1351.zip

[trurl]

1 hour ago, unburt said:

Actually, I checked just now and yes, the /mnt/user/system/docker/docker.img is the new one that's on the cache disk.

Every disk including cache is part of user shares.

 

I see you also have VMs enabled. Do you have any VMs?

 

Looks like you are going to be pretty tight with RAM even trying to run dockers. 2GB is fine for simple NAS, but at least 4GB would be my recommendation to attempt dockers, and 8GB to attempt VMs.

 

Can you add RAM?

 

[unburt]

Quote

Every disk including cache is part of user shares.

But I think a path like "/mnt/user/system/docker/docker.img" can only really be a reference to 1 file. And since I seem to have three copies, it's relevant to know which one is being referenced. I believe it's pointing to the same file as "/mnt/cache/system/docker/docker.img" because "ls" on the command line shows the same modified date. I'm not familiar with commands that would show me proof-positive of the equality of the two.

 

1. If I delete disk2 and the cache's docker.img files and then move the disk1 docker.img to the cache, I believe that would restore my original container? If it doesn't work, no big deal

2. After that, do you think it would be safe to delete /system from disk1 and disk2?

 

I don't have VMs yet but I was planning to see how it runs with this underpowered configuration. I've ordered more RAM but unfortunately it hasn't arrived yet.

Edited June 1, 2020 by unburt

[trurl]

Docker image is actually unimportant. In fact, we often recommend people delete it and recreate it since everything in it will be downloaded again when you reinstall your dockers. And the Previous Apps feature on the Apps page will reinstall your dockers exactly as they were.

 

Disable Docker Service in Settings - Docker, then delete the docker image. Do the same for Settings - VM Manager.

While these are disabled, delete the system share from all disks except cache.

Enable Docker Service will recreate docker image according to the settings, and since system share is cache-prefer, it will be created on cache where it belongs.

 

Then use the aforementioned Previous Apps feature.

[unburt]

I see. Thanks for the help trurl