Drobo 5C - Checking the Hardware You Need

Drobo 5C User Guide 14
1.1.4 Checking the Hardware You Need
To use your Drobo 5C, you will need at least two drives. If you plan to use Dual Disk
Redundancy, which protects your data against two drive failures, you will need at
least three drives.
Related topics:
Selecting Drives
Determining Drive Space Requirements
Using Power Protection