RAID 6 is an array of independent hard drives equipped with two independent and distributed checksum schemes. In general, RAID 6 is similar to RAID 5 differing in greater redundancy because two checksums are calculated and written to the array member disks. The first parity function (P) is the same as in the case of a RAID 5 (exclusive or or XOR) while the second function (Q) is much more complex (typically Reed-Solomon function).
Besides the parameters typical for a RAID 5 like the number of disks, disk order, block size, start offset, parity pattern for P function, RAID6 has a number of additional parameters:
You can read more about different types of RAID 6 here.
All these parameters can be determined automatically by ReclaiMe Free RAID Recovery.
You can find more information about preparatory actions and the recovery workflow here.