AMCC 3WARE 9690SA - Manual (Page 21)

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Chapter 3. Installing a Battery
Backup Unit
The Battery Backup Unit (BBU) is an optional add-on consisting of
a control module and a battery pack.
When used with the 3ware 9690SA RAID controller, the BBU
control module is mounted on the RAID controller and the battery
pack is installed on a remote battery board.
The BBU’s purpose is to supply power to the controller’s memory
module in the event of a system power loss. This allows the
controller to safely use write-caching for optimal performance
without exposing data to potential loss in the event of a system
power failure. When fully charged, the battery preserves the
contents of the controller cache memory for a limited period of time
(up to 72 hours). When power is restored, cached data is written to
disks.
Items in Remote Battery Installation Package
„ Battery Backup Unit (BBU) control module
„ Battery
„ Battery extension cable
„ Remote battery board with full height bracket
„ Low-profile bracket for low-profile enclosures.
„ Remote Battery Installation Guide (This chapter covers same
material)