Oyen Digital DATATALE RC-M4QJ 4-BAY RAID - Manual (Page 64)

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RAID 5
RAID 5 uses block-level striping with parity data distributed across all member
disks. It is also called Parity RAID. Every time a block is written to a disk in a
RAID 5 disk array, a parity block is generated within the same stripe. A block is
composed of many consecutive sectors on a disk. A series of blocks (a block
from each of the disks in an array) is collectively called a "stripe". The parity
information inside the parity block is not the identical copy of the source data. It
is generated via parity calculation. RAID 5 mode provides decent data protection
and fault tolerance. The speed of operation is average in comparison to other
RAID modes.
The number of disks supported by RAID 5 is 3 or 4. The storage capacity
will become all disks in total but minus 1. The capacity is limited to the size of
the smallest disks.
RAID 5
Disk 1 Disk 2 Disk 3 Disk 4
A1 A2
B1 B2
C1 Cp
Dp D1
A3
Bp
C2
D2
Ap
B3
C3
D3
If one of the disks fails, the data can be reconstructed through parity
calculation once the broken disk is replaced with a new one.
RAID 1+0
In RAID 1+0, the data is first mirrored and then striped. Under this RAID Mode, it
provides another way to achieve higher performance and data security, while
increasing complexity.
The key difference between RAID 0+1 and RAID 1+0 is that RAID 1+0
creates a striped set from a series of mirrored drives. In a failed disk situation,
RAID 1+0 performs better because all the remaining disks can continue to be
used. The array can sustain multiple drive losses as long as none of the mirror
set loses all of its drives.