Drobo 5D Using all my RAM Memory for the Cache and slowing my MAC

good day all

i noticed that when i connect my drobo to my macbook pro or my MacPro 2013, the activity moniton show that all the RAM are used as cache memory and the mac’s turns extremly slow & Hanging.

why is this happining and is there a solution for this!!!

is it a matter of Firmware issue or there is a brobplem in my drobo!!

Drobo 5D with four HDD’s each (2TB WD RED)
mSATA 256 GB used in accelerator Bay