The Mechanism
Whether using a physical PCIe RAID controller card, motherboard-based Intel RST firmware, or software-driven OS mirroring, the controller dictates the mirroring process. Failure occurs when:
- The controller card suffers an electrical failure or firmware corruption.
- A sudden power loss or system crash happens mid-write, causing the controller to lose track of whether both drives are perfectly synchronized.
The Impact on RAID 1
If a write operation is interrupted, the two drives can become desynchronized. The controller may not know which drive holds the correct, most recent version of a file. In worse cases, a failed hardware controller might falsely report both healthy drives as unreadable or unformatted.
Note: Because RAID 1 does not stripe data, if a hardware controller dies, you can usually plug either drive directly into a standard computer motherboard, and the operating system will read the data perfectly without needing the controller.
