LSI Series 518 2.3.5Disk Striping, 2.3.4Fault Tolerance, 2.3.3Consistency Check

•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 cooling fans, power supplies, and the ability to hot swap drives. MegaRAID SCSI 320-2 provides hot swapping through the hot spare feature. A hot spare drive is an unused online available drive that MegaRAID SCSI 320-2 instantly plugs 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.

2-4	Introduction to RAID