DEC AlphaServer 2100, Owner'S Manual

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SCSI Buses
Power Supply Configurations
AlphaServer 2100 systems offer added reliability with redundant
power options, as well as uninterruptible power supply (UPS)
options. Figure 3–10 shows some of the system’s power supply
options.
Power Supply
Modes The power supplies for AlphaServer 2100 pedestal systems
support three different modes of operation. In addition, UPS
options are available.
Power supply modes of operation:
1. Single power supply—Supports entry-level systems, such as
a system with two CPUs, one memory module, one diskette
drive, one CD–ROM drive, one internal StorageWorks shelf
with eight 3.5-in drives, and up to eight EISA/PCI options.
2. Dual power supply (redundant mode)—Provides redundant
power (n + 1) for entry-level and moderately configured
systems, such as a system with two CPUs, one memory
module, one diskette drive, one CD–ROM drive, one internal
StorageWorks shelf with eight 3.5-in drives, and up to eight
EISA/PCI options.
In redundant mode, the failure of one power supply does not
cause the system to shut down. Normal operation continues
with no effect on the system.
Note
The power supply mode jumper (J3) on the standard I/O
module must be installed to activate redundant mode
power.
3. Dual power supply (full power mode)—Provides full power
for system configurations beyond entry-level, such as a
system with more than two CPUs or more than one internal
StorageWorks shelf. These systems require the power of two
power supplies.
Options and Upgrades 3–47