HP Smart Array 6i Controller and 128MB BBWC - Manual (Page 46)

46 HP Smart Array 6i Controller User Guide
This configuration is useful when cost, performance, and data availability are
equally important.
Advantages:
•
Has high read performance.
•
Data is not lost if one physical drive fails.
•
More drive capacity is usable than with RAID 1+0—parity information
requires only the storage space equivalent to one physical drive.
Disadvantages:
•
Has relatively low write performance.
•
Data is lost if a second drive fails before data from the first failed drive is
rebuilt.
RAID ADG—Advanced Data Guarding
NOTE: Not all controllers support RAID ADG.
RAID ADG, like RAID 5, generates and stores parity information to protect
against data loss caused by drive failure. With RAID ADG, however, two
different sets of parity data are used (denoted by Px,y and Qx,y in the figure),
allowing data to still be preserved if two drives fail. Each set of parity data uses a
capacity equivalent to that of one of the constituent drives.
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