3Ware 720-0192-00 Manual page 22

Understanding RAID Levels and Concepts
Figure 4. RAID 6 Configuration Example
RAID 10
RAID 10 is a combination of striped and mirrored arrays for fault tolerance
and high performance.
When drives are configured as a striped mirrored array, the disks are
configured using both RAID 0 and RAID 1 techniques, thus the name RAID
10 (see Figure 5). A minimum of four drives are required to use this
technique. The first two drives are mirrored as a fault tolerant array using
RAID 1. The third and fourth drives are mirrored as a second fault tolerant
array using RAID 1. The two mirrored arrays are then grouped as a striped
RAID 0 array using a two tier structure. Higher data transfer rates are
achieved by leveraging TwinStor and striping the arrays.
In addition, RAID 10 arrays offer a higher degree of fault tolerance than
RAID 1 and RAID 5, since the array can sustain multiple drive failures
without data loss. For example, in a twelve-drive RAID 10 array, up to six
drives can fail (half of each mirrored pair) and the array will continue to
function. Please note that if both halves of a mirrored pair in the RAID 10
array fail, then all of the data will be lost.
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