To complete the installation and configuration of RAID-10 on a functioning computer that currently has one hard drive, what is the MINIMUM number of additional hard drives required?

With RAID 10, there must be at least four drives.
- Two drives are needed to create a mirror.
- Two drives are needed to stripe the data.
Because the computer already has one drive, three more drives will be required. RAID 10 provides both extra speed and fault tolerance.