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Intel® RAID Smart Battery User’s Guide
About the Intel
®
RAID Smart Battery
Intel
®
RAID Controllers and Intel
®
Integrated Server RAID Modules provide reliability, high
performance, and fault-tolerant disk subsystem management. A complete fault-tolerant strategy
requires protection for all data, including the unwritten cached data in the RAM cache. If power is
lost, the data in RAM is lost. To avoid this data loss, a battery can be added to supply power to the
RAID RAM during an AC power outage or if the AC power cord is removed.
A battery backup unit protects the integrity of the cached data on Intel RAID controllers by
providing backup power if there is a complete AC power failure or a brief power outage. The Intel
RSBBUs provide an inexpensive alternative to using an uninterruptible power supply (UPS) or act
as a second level of fault tolerance when used in conjunction with a UPS.
The cache memory available on Intel controllers can improve overall system performance. Writing
data to the controller’s cache memory is much faster than writing it to a storage device. Write
operations appear to complete very quickly at the software application level. The Intel RAID
controller then writes the cached data to the storage device when system activity is low or when the
cache is getting full. The risk of using write-back cache is that the cached data can be lost if the AC
power fails before it has been written to the storage device. This risk factor is eliminated when the
Intel RAID controller has an onboard BBU.
The Intel RSBBUs monitor the voltage level of the DRAM modules installed on the Intel RAID
controller. If the voltage drops below a predefined level, the battery backup module switches the
memory power source from the Intel RAID controller to the battery pack attached to the Intel RAID
Smart Battery Backup Unit (RSBBU). As long as the voltage level stays below the predefined
value, the Intel RSBBU provides power for memory. If the voltage level returns to an acceptable
level, the RSBBU switches the power source back to the Intel RAID controller, and all pending
writes to storage devices are completed with no data loss.
A smart battery backup unit (BBU) has built-in functionality to charge the battery pack
automatically and to communicate battery status information such as voltage, temperature, and
current to the host computer system.
The AXXRSBBU6 is a smart battery back up module using LiON technology that is compatible
with a backup auxiliary power source. Battery charging and recharging take place automatically.
The AXXRSBBU6, which features LiON battery cell technology, mounts directly to the following
Intel
®
RAID Controllers using a small board-to-board connector (daughtercard):
•
Intel
®
RAID Controller SRCSASBB8I
•
Intel
®
RAID Controller SRCSASLS4I
