Dell PowerVault MD3420 - Manual (Page 14)

Item Component Function
1 12Gbps SAS IN port (2) Provides host-to-controller SAS connection.
2 Seven segment display
sequence
Displays status or error codes for the storage array.
3 Controller power LED Lights green when controller power is on.
Turns off when controller is not powered.
4 Controller fault LED Lights amber when controller fault is detected.
Turns off when controller is operating normally
5 System identification LED Blinks blue when system identification switch push-
button on enclosure front panel is pressed.
6 Cache active or cache offload
LED
Lights green when on-board controller memory
contains data.
If AC power fails, this LED changes to indicate Cache
offload status. If the password reset function has
successfully changed the password, this LED flashes
on and off briefly.
7 Battery fault Lights amber when battery backup unit or battery has
failed.
Turns off when battery backup unit is operating
normally
8 Management port Provides a 100/1000 Mbps Ethernet connection for
out-of-band management of the enclosure.
9 Ethernet port (reserved) Reserved port.
10 12Gbps SAS IN port (2) Provides host-to-controller SAS connection.
11 USB port Reserved port.
12 Mini USB port Provides serial connection for debugging.
13 Password reset switch Activating this switch resets the password.
14 SAS OUT Port (2) Provides SAS connection for cabling to a downchain
expansion enclosure.
Using Port 0 is recommended.
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 .
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.
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