RAID 6 is the RAID level that provides double parity, allowing the system to tolerate the failure of two disks simultaneously without data loss. According to CompTIA Core 1 (220-1201) storage and RAID objectives, RAID 6 improves fault tolerance by storing two independent parity blocks across all disks in the array.

RAID 0 provides no parity or redundancy and focuses only on performance through striping. RAID 1 uses mirroring, duplicating data across two drives but does not use parity. RAID 5 uses single parity, allowing recovery from only one failed drive.

For environments such as a local bank, where data integrity and availability are critical, RAID 6 is commonly preferred due to its higher fault tolerance compared to RAID 5. Although RAID 6 has slightly lower write performance due to the additional parity calculation, the increased resilience makes it suitable for mission-critical systems.

CompTIA highlights RAID 6 as a common enterprise solution when both redundancy and reliability are priorities.