Chapter 2. RAID Array Controller

Figure 2–9 Diagram of a RAID 5 Write

Host Data

1101 0111

0110 1110

1011 0001

0010 0110

Controller divides the

data into chunksized units

and calculates parity

 

1101

0111

Striped data and parity

 

0110

1110

 

written to the array

 

1011

0001

 

 

XOr

0010

0110

 

Parity =

 

 

 

0010

 

 

There is still data left

so the Controller

repeats the Process

 

1011

0111

Striped data

and parity

 

0110

1110

 

written to the array

XOr

1011

0001

 

 

0010

0110

 

 

Parity =

 

 

 

 

 

1110

 

 

SHR-1058

RAID 5 handles drive failures in the same manner as RAID 4, except the parity is different for each stripe. The controller either uses the parity information on a stripe to reconstruct its data or simply reads the data as normal, depending on the location of the stripe’s parity drive.

EK–SMCPQ–UG. C01

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Image 48
Compaq 3000 manual Diagram of a RAID 5 Write