17.6.1 Active/Hotmaintenance 315
17.6.2 Inactive/Hotmaintenance 315
17.6.3 System-stopped maintenance 316
Chapter18 Maintainingthe Power Supply Units of the Crossbar Box 317
18.1 Configurationof the Power Supply Units 317
18.2 BeforeMaintaining a Power Supply Unit 318
18.2.1 Types of maintenance 318
18.2.2 Maintenanceflow 319
18.2.3 Precautions forreplacement 319
18.3 Enablingthe Removal of a PowerSupply Unit 319
18.3.1 Active/Hotmaintenance 320
18.3.2 Inactive/Hotmaintenance 320
18.3.3 System-stopped maintenance 321
18.4 Removinga Power Supply Unit 322
18.5 Installinga Power Supply Unit 323
18.6 Restoringthe System 324
18.6.1 Active/Hotmaintenance 324
18.6.2 Inactive/Hotmaintenance 324
18.6.3 System-stopped maintenance 325
Chapter 19 Maintainingthe Fan Units of the Crossbar Box 327
19.1 Configurationof the Fan Units 327
19.2 BeforeMaintaining a Fan Unit 328
19.2.1 Types of maintenance 329
19.2.2 Maintenanceflow 329
19.2.3 Precautions forreplacement 329
19.3 Enablingthe Removal of a FanUnit 329
19.3.1 Active/Hotmaintenance 330
19.3.2 Inactive/Hotmaintenance 330
19.3.3 System-stopped maintenance 331
19.4 Removinga Fan Unit 332
19.4.1 Accessing afan unit 332
Contents xiii