I’m new to this community! but not new to WD NAS devices. I never had the opportunity to mix drives in a NAS before until I get one for home. I put my hands on a EX4100 and stuffed with 2 Purple 4TB and 2 Gold 2TB I had at home. I decided to create a RAID 5 to achieve performance and failure tolerance knowing I will loose 4TB. RAID 5 will use all drives at 2TB - 25% of all 4 drives so I got 6TB.
What I don’t understand, is why WD will allow one to create an spanning volume with the balance of the space? Wouldn’t that decrease performance? Is it save to do that for the underlaying RAID? More important, this space come from the 2 Purple 4TB, Why I can used that space at RAID 0 or 1?
Also, if you don’t create the Spanning volume while creating the RAID you will not be able to go back to it after.