IBM System storage DS6000 Series, Redbooks

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Chapter 2. Components
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2.9.1 Battery backup units
Each DS6800 RAID controller has a battery backup unit (BBU) to provide DC power to that
controller in the event of a complete loss of power. There are thus two BBUs present in the
DS6800 server enclosure. If you compare their function to that of the different batteries in the
ESS, they are the NVS batteries. They allow un-destaged cache writes in the NVS area of
controller memory to be protected in the event of a sudden loss of AC power to both power
supplies. The BBUs will protect the contents of NVS for at least 72 hours.
From the rear of the unit, the left-hand BBU supports the upper controller, while the right-hand
BBU supports the lower controller.
Figure 2-19 DS6000 battery backup unit indicators
The DS6000 battery units have three indicators, detailed in Table 2-4.
Table 2-4 DS6800 battery backup unit indicators
DC Power (green) DC If this indicator is on solid then the power supply is
producing correct DC power. If it is blinking then the
DS6000 is not powered on. If it is off then either the
enclosure is powered off or the power supply is faulty.
Fault detected
(yellow) Exclamation mark If this indicator is on solid then the DS6000 has
identified this power supply as being faulty and it
requires replacement.
Indicator Symbol Purpose
Indicator Symbol Purpose
DC present
(green) Lightning bolt If this indicator is on solid then DC power is present. If
this indicator is off then DC power is not available from
this battery.
Battery
charging
Fault
detected
DC
present