Docker.img Making Small Writes Every 5-30 seconds?

[Inland-Empire]

Presently, my appdata, system, and domains shares are on my 1TB NVMe cache drive, formatted in btrfs.
When Docker is set to enabled on my machine, I get consistent pulses of writes to the cache, even when zero containers are active or running. This happens in the high KiB to low MiB range once every 5 to 30 seconds.

My File Activity plugin displays no activity when this happens.

I am running Unraid 6.12.4

 

Since these writes are unnecessary and add up over time, I would like to identify the cause and prevent them from happening.
 

Does anyone know how to address this problem?

[BRiT]

There is a verbose topic on this and offering different solutions or workarounds for it. I'm on mobile now, but if you search for it you should be able to find it.

[Inland-Empire]

I've done further digging over the last week and haven't found any posts about the specific phenomenon I'm talking about.

There appears to be plenty of discussion on appdata writes from docker containers, but nearly all the writes I'm seeing are actually caused by docker.img itself on the system share on my cache drive.

When using inotifywait on appdata, I saw a fair amount of activity, but most of it did not align with the cache writes I was seeing. I instead opted to try running

inotifywait -r -e modify,delete,create,close_write -m /mnt/cache

which is when I discovered that the vast majority of write activity is listed as

/mnt/cache/system/docker/ MODIFY docker.img

 

This is strange to me, and I'm looking for more information on what could be causing these constant docker.img modifications.

Does anyone know how I can reduce this activity?

[Inland-Empire]

On 12/17/2023 at 10:58 AM, BRiT said:

There is a verbose topic on this and offering different solutions or workarounds for it. I'm on mobile now, but if you search for it you should be able to find it.

While searching, I did find a comment you made some time ago where you mention configuring your containers so that no information from them is saved to docker.img.
Since I think it's possible docker containers are pushing data to that .img, how did you divert where information headed there is saved?

 

 

[Vr2Io]

On 12/17/2023 at 11:31 PM, Inland-Empire said:

 I get consistent pulses of writes to the cache, even when zero containers are active or running.

This shouldn't happen.

 

Below post have some script could help you to identify what have write to docker image / folder. So you may mapping container folder to anywhere you like.

 

Edited December 21, 2023 by Vr2Io