I'm about a month into using Unraid and my cache drive suddenly stopped being used. I have a 500gb SSD assigned to a cache pool, and my share is set to "Yes" for the cache option with that pool selected.

 

It was working great and utilizing the cache drive until a week ago. I haven't made any changes to my configuration, but I noticed that files of all sizes are now being written directly to the array. My cache drive remains virtually empty and as new files are written I see write activity on the array and not the SSD. Any ideas on what could have caused this change and how to fix it?

Edited October 4, 20214 yr by 8BitMercy

Attach Diagnostics to your NEXT post in this thread.

Attached, and noted for next time 😄

cecil-diagnostics-20211003-1837.zip

Looks like your 'C---l' share has Minimum Free of 1000000000K, in other words, 1TB. Go to the page for that user share and click on the label for Minimum Free to see what I mean.

Well, that worked. Thank you!

 

I still don't quite get the logic though. In my mind setting a value for the minimum free space on a share would cap how much data can be saved so I don't 100% fill the drives and would have no impact on the cache behavior. Can't complain that it's fixed, I just like to understand these things.

2 hours ago, 8BitMercy said:

Well, that worked. Thank you!

 

I still don't quite get the logic though. In my mind setting a value for the minimum free space on a share would cap how much data can be saved so I don't 100% fill the drives and would have no impact on the cache behavior. Can't complain that it's fixed, I just like to understand these things.

I believe that Unraid currently uses the larger of the Minimum Free settings for the cache and the share in deciding if it can use the cache.

 

I personally think these two settings should be independently applied to the cache and the array but at the moment that does not appear to be the case    I am not sure if this is intended behaviour or just how it currently works