What is the minimum value of 'Database cache size (MB)' ?

[Gregls 3]

I believe this is a straight forward question, I simply want to confirm I can set the database cache size within Emby to zero or if there is another minimum value. The reason is, I would prefer to let my Truenas ARC handle the caching. 

Thanks,

[Gregls 3]

Just had to try and adjust it. The minimum value it'll allow you to set is 64

[Q-Droid 989]

It's not advisable to do this as they are caches that serve two different purposes. The DB cache is a native page cache for faster data fetch while the ARC cache is a file I/O cache with  logic to improve file performance. The DB cache is there to prevent I/O so it doesn't even make the calls when it fetches the data from cached pages. For ARC to function the I/O calls have to be made. The DB is also smarter about which data it's going to retrieve so the ARC prefetch would end up doing more work than needed. If you're worried about double buffering then place the DB on a volume not using cache. But even if both are in use the DB is more efficient, will read/write what it needs as it populates its own cache and the size is negligible. Once it's up and running for a while the DB data should age out of the ARC cache while being retained by the DB cache.

Edited January 13, 2023 by Q-Droid

[rbjtech 5284]

Over the last couple of days alone, we've seen the default DB Cache size being a large performance bottleneck on medium-large systems.   So if anything, and to compound the advice from Q-Droid, I would increase the size of the DB cache to twice the size of the logical library.db file.    If memory is tight - then make it as large as you can over the default.  Also worth vacuuming the DB to reduce the memory requirements.

[Gregls 3]

Thanks Q-Droid for the detailed explanation. I originally assumed it was something more for systems with poor caching solutions. I didn't consider that it would be even better than letting ARC take care of it. 

I also appreciate the recommendation to double the library.db file, rbjtech. I'm surprised that mine is only 180M. I can definitely give it 1/3 GB. I had a feared it could have potentially been taking several GB.