Seagate ST12400N Bedienungsanleitung PDF herunterladen (Seite 24)

18 ASUS PCI-DA2100 User’s Manual

C. RAID Concept

RAID Concept

RAID 3

Block Striping with Dedicated Parity - Data is broken into logical blocks, the size of

a SCSI disk block, and striped across several drives. One drive is dedicated to

parity. In the event of failure, original data is re-generated from the parity informa-

tion.

Drive 0 Drive 1 Drive 2 Drive 3 Drive 4

A0 A1 A2 A3 P

A4 B0 B1 B2 P

B3 B4 C0 C1 P

C2 C3 C4 D0 P

RAID 5

Multiple Block Striping with Dedicated Parity - Sets a given number logical blocks

as a unit for striping across several drives. For small read/write, as few as one drive

may be activated for improved small record access speed. Parity information is

interleaved across the drive array. In the event of failure, original data is regener-

ated from the parity information.

Drive 0 Drive 1 Drive 2 Drive 3 Drive 4

A0-A1 A2-A3 A4-B0 B1-B2 P

B3-B4 P C0-C1 C2-C3 C4-D0

D1-D2 D3-D4 P E0-E1 E2-E3

E4-F0 F1-F2 F3-F4 P G0-G1

Required Number of Drives and Net Capacity

Following is a summary of the minimum number of drives required and the capacity

available for the different types of RAID operation:

OPERATION MIN. DRIVES CAP. AVAILABLE

RAID 0 2 T

RAID 1 2 T / 2

RAID 0 + 1 4 T / 2

RAID 3 3 T x (n - 1) / n

RAID 5 3 T x (n - 1) / n

T = Sum of the capacity of all connected drives

n = Number of connected drives

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 77 78

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Seagate ST12400N Bedienungsanleitung Seite 24