AMCC 9500S 用户手册

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Chapter 1. Introduction to the 3ware Command Line Interface
12
3ware Serial ATA RAID Controller CLI Guide 
Figure 3.  RAID 5 Configuration Example
                                      
RAID 6
RAID 6 requires a 3ware 9650SE RAID controller.
RAID 6 provides greater redundancy and fault tolerance than RAID 5. It is 
similar to RAID 5, but has two blocks of parity information (P+Q) distributed 
across all the drives of a unit, instead of the single block of RAID 5. 
Due to the two parities, a RAID 6 unit can tolerate two hard drives failing 
simultaneously. This also means that a RAID 6 unit may be in two different 
states at the same time. For example, one sub-unit can be degraded, while 
another may be rebuilding, or one sub-unit may be initializing, while another 
is verifying. 
RAID 6 requires a minimum of five drives. Performance and storage 
efficiency also increase as the number of drives increase.