HP 166207-B21 Advanced Data Guarding Option Software Reference Guide - Page 8

1 Overview of RAID ADG Advanced Data Guarding (RAID ADG) is a fault-tolerance method that uses two different and independent sets of parity data. A logical volume using this exceptionally high level of data protection can tolerate the simultaneous failure of two hard drives without suffering downtime or data loss. B1 B3 P5,6 Q7,8 B2 P3,4 Q5,6 B7 P1,2 Q3,4 B5 B8 Q1,2 B4 B6 P7,8 Figure 1-1: Array using RAID ADG, showing data blocks (B) and two parity data sets (P, Q) RAID ADG also makes efficient use of drive space, since the two sets of parity data occupy a total drive space equivalent to two hard drives. The amount of drive space used for parity data is independent of the total number of hard drives in the logical volume. Compaq Advanced Data Guarding Option Software Reference Guide 1-1