How is the SSD cache actually used? Would I be wasting a pair of 256gb SSD's would a pair of 64gb's basiclly be better used instead? This is just cache after all.

 

Doh! nevermind after reading unraid manual I see it's used as storage untill set task moves it.. guess I should RTFM first 

Under unRAID 6+ the cache drive is also the defacto "application" drive.  It's where the Docker image goes, data associated with your Dockers, and where VM images go.  You can place them elsewhere but the cache drive is the default.  You can also still use it for it's original purpose, which is the high speed write caching of new files being written to the storage array.

 

64GB is small but functional for a cache drive.  It could easily handle a handful of Dockers that don't have big storage requirements.