Drive 1

Drive 2

Drive 3

Drive 4

Data A	Data A		mA	mA
Data B	Data B		mB	mB
Data C	Data C		mC	mC
Original Data			Mirrored Data

Minimum Number of Drives: 4
Strengths: Highest performance, highest data protection (can tolerate multiple drive failures).
Weaknesses: High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required; Requires minimum of four drives.