What is required for RAID 5 to function effectively?

For RAID 5 to function effectively, a minimum of three drives is necessary. This configuration is designed to provide both data redundancy and improved performance through striping with parity. In RAID 5, data and parity information are distributed across all drives in the array. This means that if one drive fails, the data can still be reconstructed using the remaining drives and the parity information, thus ensuring fault tolerance.

Using fewer than three drives would not allow RAID 5 to write the necessary parity information while also maintaining the redundancy that is characteristic of this RAID level. With only one or two drives, the system cannot effectively implement both data striping and parity distribution, which is critical for the RAID 5 functionality. Therefore, the requirement for at least three drives is essential to achieve the desired balance of redundancy and performance in a RAID 5 setup.