AMCC 9550SXU-8LP Manual - Página 14
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Striped Data with Distributed Double Parity — RAID 6
Disk #1
Disk #2
Disk #3
Disk #4
P1 Parity
Q1 Parity
Block 1
Block 2
Block 4
P2 Parity
Q2 Parity
Block 5
Common RAID Levels
Block 7
Block 8
P3 Parity
Q3 Parity
Block 10
Block 11
Block 12
P4 Parity
RAID 0, 1, 5, 10 and JBOD
Striped Data with Distributed Double Parity — RAID 6
RAID 0 "Striping"
A
B
E
F
I
J
M
N
RAID 0 "Striping"
RAID 5 "Rotational Parity"
A
B
C
D
E
F
G
H
A 0
B 0
I
J
K
L
A1
B1
1 Parity
M
N
O
ETC. . .
A2
2 Parity
3 Parity
B3
Hardware vs. Software RAID
All AMCC 3ware RAID controllers incorporate onboard processors to deliver true hardware RAID. Software RAID schemes use the system's
processor, exploit host memory, compromise reliability and potentially rob the system of as much as 60% of its CPU cycles just to process
RAID calculations.
RAID 1 "Mirroring"
Disk #5
Block 3
Block 6
Block 9
Q4 Parity
RAID 0 "Striping"
A
B
C
E
F
G
• Applications requiring high bandwidth
I
J
K
C
D
performance but no fault tolerance
M
N
O
G
H
• Video production/editing
K
L
• Pre-press applications
O
ETC. . .
A
• Most versatile RAID level providing performance,
B
fault tolerance and storage efficiency
C 0
0
Parity
• Video production/editing
C
D1
• File and applications servers
D
C2
D2
• Database servers
D3
C3
• Email servers
SATA Disk
• News servers
SATA Disk
• Internet/Intranet
SATA Disk
SATA Disk
RAID 10 "Striped Mirror"
Mirror
3 Parity
B3
C3
RAID 5 "Rotational Parity"
A 0
B 0
C 0
0
Parity
A1
B1
D1
1 Parity
A2
C2
D2
2 Parity
D3
B3
C3
3 Parity
RAID 1 "Mirroring"
D
H
L
A
A
1
ETC. . .
=
B
B
1
C
C
1
D
D
1
RAID 1 "Mirroring"
A
1
Stripe
=
B
1
C
1
D
1
JBOD = Just a Bunch of Disks
JBOD refers to an unconfigured disk attached to a RAID controller
• No fault tolerance
D3
SATA Disk
SATA Disk
SATA Disk
SATA Disk
RAID 1 "Mirroring"
RAID 10 "Striped Mirror"
• Provides fault tolerance and a read speed
SATA Disk
Mirror
advantage over non-RAID disks
A
A
1
Stripe
• Applications requiring high availability
SATA Disk
=
B
B
1
• Accounting
1
D1
D1
SATA Disk
C
C
1
• Payroll
Drive 0
Drive 1
Stripe
D
1
D
SATA Disk
• Financial
D2
D2
1
Drive 2
Drive 3
RAID 10 "Striped Mirror"
Mirror
• Data is first mirrored, then striped across across
the drives to provide double drive failure
protection without the parity calculation
1
D1
D1
performance penalty of RAID 5 and RAID 6.
Drive 0
Drive 1
The mirror provides the redundancy.
D2
D2
1
• Ability to recover from a drive failure in either
mirrored set
Drive 2
Drive 3
SATA Disk
SATA Disk
SATA Disk
RAID 10 "Striped Mirror"
Mirror
D1
D1
1
Drive 0
Drive 1
D2
D2
1
Drive 2
Drive 3