EMC Symmetrix DMX-3 User Manual

208
EMC Symmetrix DMX-3 Product Guide
Data Integrity, Availability, and Protection
RAID 6 (6+2)
A RAID 6 (6+2) configuration consists of eight Symmetrix devices
with parity and data striped across each device. With this option,
effectively 75 percent of the total storage capacity of a RAID 6 device
is available for storing data.
Figure 46 on page 208 shows a RAID 6 (6+2) data/parity layout.
Figure 46 RAID 6 (6+2) data/parity layout
RAID 6 (14+2)
A RAID 6 (14+2) configuration consists of sixteen Symmetrix devices
with parity and data striped across each device. With this option,
effectively 87.5 percent of the total storage capacity of a RAID 6
device is available for storing data.
0
SYM-001302
7
D1 D2 D3 D4 D5 D6 N N N N N N N N N N N
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
16 14
15
13
14
15
12
13
14
15
11
12
13
14
15
10
11
12
13
14
15
9
10
11
12
13
14
15
8
9
10
11
12
13
14
15
7
8
9
10
11
12
13
14
15
6
7
8
9
10
11
12
13
14
15
5
6
7
8
9
10
11
12
13
14
15
4
5
6
7
8
9
10
11
12
13
14
15
3
4
5
6
7
8
9
10
11
12
13
14
15
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
D8
P0
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
D7
H0
H1
H2
H3
H4
H5
H6
H7
H8
H9
H10
H11
H12
H13
H14
H15 16
16
16
16
16
16
16
16
16
16
16
16
16
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
10
11
0
1
2
3
4
5
6
7
8
9
10
11
0
1
2
3
4
5
6
7
8
9
10
11
12
13 10 12
0
0
0 1
1
2
1
2
3
0
1
2
3
4
0
1
2
3
4
5
D1
Physical disk 1, in this slice there are 6 data drives, from D1 to D6
D7
Physical disk 7, in this slice it contains the Horizontal Parity
D8
Physical disk 8, in this slice it contains the Diagonal Parity
N
Null disk is a non existent drive whose contents is always zero but exists
solely for the purpose of the RAID calculations
One track of 64 K, made by 16 elements of 4 K each
cy/hd
9/9
cy/hd
9/D
cy/hd
10/2
cy/hd
10/6
cy/hd
10/A
10/E
cy/hd
Slice # 18
cy/hd
P
cy/hd
DP
Special diagonal
16
H
Full track is calculated XOR all 17 horizontal tracks
Horizontal parity doesn’t include the diagonal parity
P0
4 K of the Diagonal parity track
P0
is calculated by XOR all 4 K chunks marked
P1
is calculated by XOR all 4 K chunks marked
0 and XOR all chunks marked
16
1 and XOR all chunks marked
16

EMC Symmetrix DMX-3 Specifications

General

Brand	EMC
Model	Symmetrix DMX-3
Category	Storage
Language	English