RAID Technology Overview - September 2007

RAID ADG is most useful when data loss is unacceptable but cost must also be minimized. The
probability that data loss will occur when arrays are configured with RAID ADG is less than
when they are configured with RAID 5. For more information, see Appendix A (page 21).
Figure 2-5 Advanced Data Guarding, Showing Parity Information (Px,y and Qx,y)
The advantages of RAID ADG are as follows:
• High read performance.
• High data availability—any two disks can fail without loss of critical data.
• More disk capacity usable than with RAID 1+0; parity information requires only the storage
space equivalent to two physical disks.
The only significant disadvantage of RAID ADG is a relatively low write performance (lower
than RAID 5), due to the need for two sets of parity data.
18 Smart Array Controller Supported RAID Configurations