￿A combination of any two of the above conditions

2.3.3Consistency Check

A consistency check verifies the correctness of redundant data in a RAID array. For example, in a system with distributed parity, checking consistency means computing the parity of the data drives and comparing the results to the contents of the parity drives.

2.3.4Fault Tolerance

Fault tolerance is achieved through auto detection of failed drives, rebuilds with hot spare drive, the ability to hot swap drives, Configuration on Disk capability, and support for self-monitoring analysis and reporting technology (SMART). MegaRAID SCSI 320-0 provides hot swapping through the hot spare feature. A hot spare drive is an unused online available drive that MegaRAID SCSI 320-0 can instantly plug into the system when an active drive fails.

After the hot spare is automatically moved into the RAID subsystem, the failed drive is automatically rebuilt. The RAID disk array continues to handle request while the rebuild occurs.

2.3.5Disk Striping

Disk striping writes data across multiple disk drives instead of just one disk drive, as shown in Figure 2.1.

2-4Introduction to RAID

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