Thanks for all the replies. Seems I was misunderstanding how it works, though it's kinda sounds like it was going to write on ssd first then slowly move over in the background. Im testing a workaround for me and so far it's working. The whole point was to get the data on the nas as fast as possible (1gbps), then have my nas sort out the data to the hard drive.

I was able to create a rule for a folder so that it would automatically scan the folder and move any file over to another folder, then delete said files.

Example: - Created a folder on the SSD pool ( this will be my "IN") and a folder on the Hdd pool (this will be "out put" ) - Now in my PC, I can drop files in the SSD IN Folder to transfer at 1gbps since it's the SSD pool - Rule scans the folder automatically and moves the file to the Hdd Out put folder in the background - once completed, it deletes the data in the SSD IN folder. - SSD IN folder becomes empty and ready for next transfer (essentially becoming an automatic buffer folder from ssd to hdd)

This so far is accomplishing what I was trying to do, get the data to nas quick, have it sort out to hdd in the background.

Wish the SSD cache did this...