Dell PowerVault MD3220 - Manual (Page 34)

34 Planning: RAID Controller Modules
RAID Controller Module—Additional Features
Battery Backup Unit
Each RAID controller contains a two-cell Lithium ion nanopolymer battery
backup unit (BBU). It provides power to the RAID controller module in the
event of a power outage. For information on removing and installing the BBU,
see "RAID Controller Module Backup Battery Unit" on page 214.
NOTE: For virtual disks, the RAID controller firmware changes the data cache
setting based on the state of the battery. If the battery is missing or does not have
sufficient charge, the controller flushes the cache and sets the write cache
attribute to Write Through for all virtual disks. When the battery is replaced, Write
Back is re-enabled.
18 SAS IN 3 port
link/fault LED
Lights green when all four links are connected.
Lights amber when one to 3 links are disconnected.
Off when all links in the port are disconnected or cable is
disconnected.
19 Management
port speed LED
Lights green when ethernet connection is operating at 1000
Mbps.
Lights amber when ethernet connection is operating at 100
Mbps.
Off when ethernet connection is operating at 10 Mbps or is
not active.
20 Management
port activity LED
Lights green when ethernet connection is active.
Off when ethernet connection is not active.
21 Management
port Ethernet
connector
Provides a 100/1000 Mbps Ethernet connection for out-of-
band management of the enclosure.
Item Component Function
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