uiop

16TB is partition/volume limit. Whatever goes below that is fine.
 
You can mount drives separate, but can't join them into one volume that is larger than 16TB. It's 32bit OS/hardware limit.

@uiop The 32-bit architecture limitation is actually on Linux page cache which is used by file systems, therefore limiting the max usable size of a partition or logical volume to 16TB. This doesn't stop you to have several partition (or logical volume) of <16TB.
 
Here an example taking in consideration 4x 12TB HDD :
 
If you use mdadm and you setup a RAID6 or RAID10 array, you will have an array of 24TB of usable space .
You can then create 2x partition of 12TB or any other combination that would max out the array size, till a each partition doesn't exceed 16TB.
 
If you use lvm and you setup a Volume Group (VG) with the 4 drives (PV), you will get a volume group of 48TB of usable space.
You can then create as many (max: 255) Logical Volume (LV) to max out the VG size till each LV doesn't exceed 16TB.
 
Actually a good approach is to use LVM on top of MDADM Raid, this way it gives flexibility to resize your partition, or i should say Logical Volume (LV).
 
After you can of course neither use mdadm or lvm, and just setup individually each disk... till you follow the rules that you can't create a single partition bigger than 16TB, but you can create several partition.
 
Hope it clarifies.