EMC CX500I Configuration Guide - Page 36
Second Disk, Third Disk, Fourth Disk, Stripe, Element, User Data, Parity Data, Data Block, Bytes - cx500 flare
 |
View all EMC CX500I manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 36 highlights
RAID Types and Trade-offs Figure 2-3 shows user and parity data with a data block size of 2 Kbytes in a RAID 3 Group. Notice that the byte addresses proceed from the first disk to the second, third, and fourth, then the first, and so on. Stripe Element Size Data Block Bytes First Disk 0-511 2048-2559 4096-4607 6144-6655 8192-8603 ... Second Disk 512-1023 2560-3071 4608-5119 6656-7167 8604-9115 ... Stripe Size Third Disk 1024-1535 3072-3583 5120-5631 7168-7679 9116-9627 ... Fourth Disk 1536-2047 3584-4095 5632-6143 7680-8191 9628-10139 ... Parity Parity Fifth Disk Parity Parity Parity ... User Data Parity Data EMC1816 Figure 2-3 RAID 3 Group RAID 3 differs from RAID 5 in one major way. With a RAID 3 Group, the parity information is stored on one disk; with a RAID 5 Group, it is stored on all disks. RAID 3 can perform sequential I/O better than RAID 5, but does not handle random access as well. FLARE™ Operating Environment 2.07 improved RAID 3 processing in several ways: ◆ Use of the write cache is now equivalent to RAID 5 ◆ I/O sizes to disk have been increased ◆ Maximum host transfer size has been increased. RAID 3 is best thought of as a specialized RAID 5, where the expectation is either large or sequential I/O. However, with write cache active for RAID 3, RAID 3 is more flexible than in previous releases, and can handle some level of concurrency. A RAID 3 Group works well for applications that use I/Os of blocks 64 Kbytes and 2-6 EMC CLARiiON CX300, CX500, CX500i, and CX700 Storage Systems Configuration Planning Guide
-
1 -
2
-
3
-
4
-
5
-
6
-
7
-
8
-
9
-
10
-
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
-
26
-
27
-
28
-
29
-
30
-
31 -
32 -
33 -
34 -
35 -
36 -
37 -
38 -
39 -
40 -
41 -
42
-
43
-
44
-
45
-
46
-
47
-
48
-
49
-
50
-
51
-
52
-
53
-
54
-
55
-
56
-
57
-
58
-
59
-
60
-
61
-
62
-
63
-
64
-
65
-
66
-
67
-
68
-
69
-
70
-
71
-
72
-
73
-
74
-
75
-
76
-
77
-
78
-
79
-
80
-
81
-
82
-
83
-
84
-
85
-
86
-
87
-
88
-
89
-
90
-
91
-
92
-
93
-
94
-
95
-
96
-
97
-
98
-
99
-
100
-
101
-
102
-
103
-
104
-
105
-
106
-
107
-
108
-
109
-
110
-
111
-
112
-
113
-
114
-
115
-
116
-
117
-
118
-
119
-
120
-
121
-
122
-
123
-
124
-
125
-
126
-
127
-
128
-
129
-
130
-
131
-
132
-
133
-
134
-
135
-
136
-
137
-
138
-
139
-
140
-
141
-
142
 |
 |
