Digital Equipment Corporation RAID Array 3000 storage subsystem User's Guide download pdf (Page 43)

Chapter 2. RAID Array Controller

EK–SMCPO–UG. A01 2–15

2.6.4 RAID 4

RAID 4 breaks up host data into chunks, calculates parity by performing an ex-

clusive-or on the chunks, and then writes the chunks to all but one drive in the

array and the parity data to the last drive. When the host requests data from the

disk drives, the controller retrieves the chunks containing the addressed data, re-

constitutes the data from the chunks, and passes the data to the host.

Figure 2–7 Diagram of a RAID 4 Write

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 93 94

RAID Array 3000 Storage 1
Subsystem 1
Contents 3
3 Maintenance 4
4 Expansion Pedestal Option 5
5 Second Controller Option 5
Figures (continued) 6
EK–SMCPO–UG. A01 vii 7
Revision Record 9
About This Guide 11
Associated Documents 12
Conventions 12
Conventions ( 13
Support and Services 13
Who to contact in Europe 14
Product Overview 15
1–2 EK–SMCPO–UG. A01 16
Chapter 1. Product Overview 17
1.2 Pedestal Features 18
1.3 Pedestal Cabinet 18
1.4 Pedestal Components 20
1.4.2 RAID Array Controller 20
EK–SMCPO–UG. A01 1–7 21
1–8 EK–SMCPO–UG. A01 22
1.4.6 UltraSCSI Buses 23
1–10 EK–SMCPO–UG. A01 24
1.5 Specifications 26
RAID Array Controller 29
2.2 Controller Features 30
EK–SMCPO–UG. A01 2–3 31
EK–SMCPO–UG. A01 2–5 33
2–6 EK–SMCPO–UG. A01 34
EK–SMCPO–UG. A01 2–7 35
2.5 Performance Enhancements 36
2.5.1 Custom Components 36
EK–SMCPO–UG. A01 2–9 37
2.6 RAID Levels Supported 38
2.6.1 RAID 0 39
2–12 EK–SMCPO–UG. A01 40
Figure 2–4 RAID 0 Write 40
2.6.2 RAID 1 41
2.6.3 RAID 0+1 41
2–14 EK–SMCPO–UG. A01 42
Table 2–5 RAID 0+1 Example 42
2.6.4 RAID 4 43
2.6.5 RAID 5 44
EK–SMCPO–UG. A01 2–17 45
2.6.6 JBOD 46
2.7 System Parameters 46
EK–SMCPO–UG. A01 2–19 47
Table 2–6 System Parameters 47
Parameter Description 47
2.8 Redundant Operation 48
2.8.1 Initialization 48
2.8.2 Message Passing 48
2.8.3 Failover 48
2.9 Environmental 49
2.9.2 Voltage Monitoring 50
EK–SMCPO–UG. A01 2–23 51
2.9.3 Temperature Monitoring 52
Maintenance 53
3.3 SBB Status LEDs 54
3.4 Controller LEDs 55
3.5 EMU Error Reporting 56
3.5.1 EMU Error Conditions 56
Chapter 3. Maintenance 57
EK–SMCPO–UG. A01 3–5 57
3.6.2 Replacing an SBB 58
EK–SMCPO–UG. A01 3–7 59
Figure 3–4 Replacing an SBB 59
3–8 EK–SMCPO–UG. A01 60
EK–SMCPO–UG. A01 3–9 61
3–10 EK–SMCPO–UG. A01 62
EK–SMCPO–UG. A01 3–11 63
3.6.14 Replacing the UPS 64
EK–SMCPO–UG. A01 3–13 65
3–14 EK–SMCPO–UG. A01 66
EK–SMCPO–UG. A01 3–15 67
3–16 EK–SMCPO–UG. A01 68
EK–SMCPO–UG. A01 3–17 69
3–18 EK–SMCPO–UG. A01 70
EK–SMCPO–UG. A01 3–19 71
3–20 EK–SMCPO–UG. A01 72
Expansion Pedestal Option 73
4–2 EK–SMCPO–UG. A01 74
EXPANSION PEDESTAL 75
4–4 EK–SMCPO–UG. A01 76
EK–SMCPO–UG. A01 4–5 77
4–6 EK–SMCPO–UG. A01 78
J16 (see Figure 4–7) 79
4–8 EK–SMCPO–UG. A01 80
Remove Knockout 81
4–10 EK–SMCPO–UG. A01 82
EK–SMCPO–UG. A01 4–11 83
4–12 EK–SMCPO–UG. A01 84
Figure 4–16 85
4–14 EK–SMCPO–UG. A01 86
Second Controller Option 87
5.2 Installation Procedure 88
EK–SMCPO–UG. A01 5–3 89
5–4 EK–SMCPO–UG. A01 90
EK–SMCPO–UG. A01 5–5 91
Reader’s Comments 93

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