RAID Array 3000 Controller Shelf

Figure 2–7 Diagram of RAID 0+1 Write

Host Data

Controller divides

Striped data written

the data into

 

to half the drives

1110

chunksized units

 

1101

 

 

 

 

 

1110

 

 

1011

 

 

 

 

1101

 

Striped data mirrored

 

 

 

 

 

1011

 

 

 

 

to the remaining drives

 

 

 

 

 

 

 

 

 

SHR-1056

In the event of a drive failure, a RAID 0+1 array will enter degraded mode and continue to operate by substituting the failed drive with its mirror.

When the controller creates a RAID 0+1 set, it first sorts the drives by channel number and SCSI ID. Then it stripes the data across every other drive and forms a mirrored pair with the first two drives, another mirrored pair with the second two drives, and so on. Table 2–4 describes how the controller uses the drives in a RAID 0+1 set.

Table 2–4 RAID 0+1 Example

Drives Selected

Channel 1, ID 0

Channel 1, ID 1

Channel 1, ID 2

Channel 2, ID 0

Channel 2, ID 1

Channel 2, ID 2

Function

First member of stripe set.

Mirror of channel 1, ID 0

Second member of stripe set

Mirror of channel 1, ID 2

Third member of stripe set

Mirror of channel 2, ID 1

2–12

EK–SMCPQ–UG. C01

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Image 45
Compaq 3000 manual Diagram of RAID 0+1 Write, RAID 0+1 Example