RA8000 and ESA12000 Storage Subsystems
3–2
387404–001
EK–SMCPR–UG. A01
3.1.1 Connecting the EMU Communications Bus
In an expansion configuration you must establish communications between the master
EMU and each of the expansion EMUs. This is accomplished by connecting a
communications port on each EMU to a communications port on another EMU. By
establishing an EMU communications bus chain you ensure that the master EMU can
monitor and control all the enclosures in the UltraSCSI subsystem.
Compaq recommends that you use a BN25G cable no longer than 4 m (13.1 ft.) to
connect the EMUs.
3.1.2 Setting the Temperature Sensors
There are three temperature sensors in each UltraSCSI enclosure – two on the rear of the
backplane in the top middle and one mounted on the EMU module.
The EMU sensor monitors the input, or ambient, air temperature while the two enclosure
sensors monitor the exhaust air temperature. The exhaust air temperature is higher than
the ambient air temperature during normal operation.
In an expansion configuration (two or more enclosures operating with the same controller)
you only set the master EMU temperatures. The temperature set points for the other
UltraSCSI enclosures, the “slaves”, automatically change to match the setting for the
master EMU.
Users have the option of setting the temperature at which an individual sensor reports an
overtemperature condition. The desired temperature is entered in degrees Celsius within
the range of 0
°
C (32
°
F) through 49
°C (120°
F). See Table 3–1 for the relationship
between
°
C (Celsius) and
°
F (Fahrenheit).
Tables 3–2 and 3–3 describe the rules to adhere to when setting temperature set points.
For detailed instructions about using the
set emu
commands, refer to the array
controller CLI documentation.
Should the ambient temperature regularly be higher than 35
°
C (95
°
F), Compaq
recommends you select a temperature setting that ensures the continued operation without
endangering the components. Setting the temperature sensors to the highest expected
ambient temperature should ensure optimum operation.
CAUTION
To ensure proper operation, enter all temperatures in °C.
You cannot enter temperatures as fractions, decimals, or in
°F.