Areca ARC-1130 User Manual

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RAID 1E is a combination of RAID 0 and RAID 1, combing strip-

ping with disk mirroring. RAID Level 1E combines the fast per-

formance of Level 0 with the data redundancy of Leve1 1. In 

this configuration, data is distributed across several disk drives, 

similar to Level 0, which are then duplicated to another set of 

drive for data protection. RAID 1E has been traditionally imple-

mented using an even number of disks, some hybrids can use an 

odd number of disks as well. Illustration is an example of a hy-

brid RAID 1E array comprised of five disks; A, B, C, D and E. In 

this configuration, each strip is mirrored on an adjacent disk with 

wrap-around. In fact this scheme - or a slightly modified version 

of it - is often referred to as RAID 1E and was originally proposed 

by IBM. When the number of disks comprising a RAID 1E is even, 

the striping pattern is identical to that of a traditional RAID 1E, 

with each disk being mirrored by exactly one other unique disk. 

Therefore, all the characteristics for a traditional RAID 1E apply 

to a RAID 1E when the latter has an even number of disks. Areca 

RAID 1E offers a little more flexibility in choosing the number of 

disks that can be used to constitute an array. The number can be 

even or odd.

RAID 3 provides disk striping and complete data redundancy 

though a dedicated parity drive. RAID 3 breaks up data into 

smaller blocks, calculates parity by performing an exclusive-or 

on the blocks, and then writes the blocks to all but one drive in