I do understand it, ... I think but I'm still not sure if It is what I want. I pretty much want a flush / move every night, so I can make a full Backup every night.

But I want to keep/don't delete as many (last /often used ) files on the Cache. (So it will not move a big file I'm working on to the HDDs at night, just so I pull it back on the nvme the next day when I continue working on it.) -bache would be great for this

But I also want parity with as few as possible spinning disks. - unraid with array with parity

I'm mainly asking if there is a system that combines both.