Cache free space decreases each time mover runs

[Hastor]

I've got a fairly recently set up array, using mostly default settings. It's my first Unraid array, but things have been going well. However, I've had an interesting issue and wonder if it is a setting I am missing, or something I can clear...

 

I have a cache pool of 2x500GB SSD drives. Every day when I see mover has run, there is less free space on the cache. It now has over 400MB used, and was just over 200 a day or two ago. If I click the folder to browse from the UI, it contains only empty folders (one is empty except for 2 empty subfolders). As I'm using this strictly for NAS, I deleted the other files that Unraid might put here via the Unraid UI for now, before I'd even added the cache. Cache was added with purely default cache settings aside from setting a min free space.

 

I have moved a large amount of files in the past couple days, to where the cache got full and it wrote directly to the storage drives a couple times. However, as of now, according to browsing files via the Unraid UI, as well as checking the cache via ssh, the cache has nothing on it but empty folders. The Cache when viewing the 'Main' tab says it has 416MB on it though. Over 400MB is a fair amount on a 500GB disk, especially when it is growing. Is there a log that's increasing? I need to figure out how to get this to stop in any case, as my cache will be useless before long at this rate...

My cache and array are both set to min 150GB free space, so it is eating up an even higher % of what I want to use. I'd expect a little tied up due to formatting, but it was tiny to start with.

 

Diagnostics are attached, I appreciate any help! As usual, sorry if this is covered, but I searched, and haven't found anything so far.

 

EDIT: Stopping and starting the array seems to have cleared it back to only 4MB used, just like it started. I don't want to stop/start my array every couple days though... but thought this may be helpful information. Diagnostics are from before stopping the array while the seemingly phantom space was taken.

megachurch-diagnostics-20210519-2100.zip

Edited May 20, 2021 by Hastor

[John_M]

9 minutes ago, Hastor said:

Over 400MB is a fair amount on a 500GB disk

 

It's actually less than 0.1 %, which is really very little and nothing to worry about at all. It's the file system overhead.

 

[Hastor]

Just now, John_M said:

 

It's actually less than 0.1 %, which is really very little and nothing to worry about at all. It's the file system overhead.

 

Yeah it isn't a ton, but at the rate it was growing, it seemed like a lot, if it got to 400MB after only a couple days uptime on a 500GB cache, if it kept up that rate... that was my main worry. It was seeming like a bigger % in my mind all the same as I just got off work and am tired and didn't think it fully through as well! As long as it doesn't add another 200MB every single day, I think it should be fine.

[John_M]

I don't believe it will continue to increase, unless you add files, of course. I think most of it is used here:

 

   Global reserve:		 396.97MiB	(used: 0.00B)

 

Global reserve is a small amount of space that's permanently set aside for use in an emergency, such as when the file system becomes critically full. It's capped at 512 MiB. See here.