What does double-parity RAID protect against?

Double-parity RAID is designed to provide a higher level of data protection by utilizing two parity blocks which store the equivalent of two distinct sets of information that can help reconstruct data. This method allows the system to tolerate the failure of two hard drives simultaneously without experiencing data loss.

When a hard drive fails, the data from that drive can be reconstructed using the remaining drives and the two sets of parity data. Therefore, the primary function of double-parity RAID is to safeguard against multiple drive failures, making it more resilient compared to other RAID levels that only offer protection against a single drive failure.

This advanced approach also means that if two drives fail at the same time, the data remains recoverable, which is critical for maintaining data integrity in environments where downtime or data loss can have significant consequences.