Cache Drive - Constant Writes + Question

[DieAngst]

I have a question regarding the cache drive as I've tried to find an answer but haven't done so successfully. I've got a 1tb nvme cache drive that's formatted to ZFS. All of my appdata and docker directory sits on this. This drive was used a media storage drive for jellyfin but now only contains appdata and docker directory.

 

I use docker containers mainly for media and have created a docker compose file for this. The file contains all the dockers I need for the media side of things. I've not had any issue with the file but I am suspicious that I may have done something wrong that's leading to the writes.

What I am seeing is constant writes on the cache drive. normally 8.2 kb/s and the max being 600kb/s. I've run iotop and I am seeing the dockerd is constantly updating the log. From time to time, either sonarr or radarr pops up. These writes are happening every few seconds. The main one being:

 

dockerd -p /var/run/dockerd.pid --~og-level=fatal --storage-driver=zfs

 

From my understanding, this is the docker demon writing to the log file. I would like to confirm this please.

 

My nvme drive currently has 55,883,412 Host Write Commands. My question is if this is normal. That the cache drive should constantly be writing due to the docker containers working? I just don't want to kill my nvme cache drive because I did something wrong that leading to excessive writes.

 

Please let me know if you need any reports or logs. I will do my upmost to provide them.

 

My apologies if this is a stupid or basic question. I am new to Unraid and currently learning all the ins and outs of it. Please bear with me, I am keen learner looking for guidance. Thank you for your time.

[Vr2Io]

This normal.

[DieAngst]

On 1/7/2024 at 9:53 PM, Vr2Io said:

This normal.

Thank you for the response and sorry for my delayed response. Marked your comment as solution.

[south_of_heaven]

Was having a similar issue. Thank you for asking about this. I was confused about the frequent intermittent bursts of 200ish kb/s writes to cache. I figured that they were expected with normal docker container use writing to log during idle.

 

While looking for an answer I saw that there was a problem with an old Unraid version where several people reported having large amounts of data written to the cache.