Yes, there is a difference between RAID 0+1 and RAID 1+0. System administrators
and vendors are sometimes confused about the difference. I once ran into a RAID controller
that supposedly supported RAID 10, but upon implementation, I discovered that
the controller really implemented RAID 0+1. That difference had a negative consequence,
which I hope to clarify shortly.
The difference between 0+1 and 1+0 isn??™t simply academic. There is a major difference
in terms of performance and data protection. Don??™t let anyone simply shrug their
shoulders at you and insist that the two approaches are basically the same. Be sure you
know which type you??™re implementing. RAID 0+1 is a mirror of stripes; RAID 1+0 is a
stripe of mirrors.
nCaution Some RAID controller hardware vendors claim to support RAID 10, while in practice, they really
implement 0+1. Don??™t rely solely on published specs or documentation; verify that when vendors say RAID
10, they mean RAID 10.
RAID 0+1 tends to performslightly better than RAID 10. This performance increase is
due to focusing on striping before mirroring, as shown in Figure 10-7.
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