The RAID level that provides the highest possible capacity for a storage array is RAID 0. RAID 0 is a type of RAID level that provides performance enhancement by using striping. Striping means dividing data into blocks and distributing them across multiple disks to increase speed and capacity. RAID 0 does not provide any fault tolerance or redundancy, as it does not use any parity or mirroring techniques. RAID 0 uses all of the available disk space for data storage, without losing any space for overhead. Therefore, RAID 0 provides the highest possible capacity for a storage array, but also has the highest risk of data loss.
Reference: https://www.thinkmate.com/inside/articles/what-is-raid