AngrysDad

Hi everyone, Total Noob here. I've had my unraid server going for a total of about 8 hours now. I'm currently transferring data from my old Drobo onto my newly built unraid rig. Currently, I have 4 brand new 4Tb HDD in my array with 2 data disks and 2 parity disks, with a 1Tb Samsung Evo 970 plus as Cache. This gives me just under 8Tb of storage space with dual parity (I think - correct me if I'm wrong). I would like to repurpose 2 of the HDD's from my old Drobo in the new unraid rig. These are a nearly new 4TB Western Digital Red, and a generic 5Tb Samsung HDD. My question is: Is it possible to add these disks into the system and increase my storage space and still retain dual parity (ie 2 disk failures without losing data)? If this is possible, how do I assign each disk to set this up? I hope someone out there takes pity on a noob. I thank you emphatically for any help that anyone can offer.