Unmanaged drives -> how to handle?

Good morning everyone,

I've been pulling my hair trying to figure this out. Been reading the documentations but i can't find anything related to "unmanaged drives".

We got a Dell Storage SC5020, originally came with 15 SSD drives. Then we bought 15 more of the same HD model to fill the SC5020.

All good there, but for some reason:

5 drives joined the "Assigned folder" of disks and populated the RAID.

while 2 are "managed" and doing nothing

and 2 ended up "unmanaged" doing i guess even less.

And lastly, got 6 drives that ended up in the "Unassigned folder" and are just sleeping there with 1 being "denied with a red X". Also all these 6 drives are "unmanaged".

I'm trying to figure out how to put those drives as "managed" and add them to my RAID".

Hoping all this makes some sense.

Here's a picture of the situation :

I tried to "Manage unassigned Disks" but i get an error : Requested disk(s) must be unassigned for this operation, found assigned disk even though i only select disks 25 to 29.

and Rebalance the raid shows no disks to select

Any insight would be greatly appreciated.

thanks in advance

Eric