Dell 6 series User Manual page 138

Battery Backup Unit (BBU)
The battery backup unit protects the integrity of the cached data on the
controller by providing backup power if there is a complete AC power failure or
a brief power outage.
BIOS
Acronym for basic input/output system. Your system's BIOS contains programs
stored on a flash memory chip. The BIOS controls the following:
communications between the microprocessor and peripheral devices, such as
the keyboard and the video adapter, and miscellaneous functions, such as
system messages.
BIOS Configuration Utility
The BIOS Configuration Utility configures and maintains RAID disk groups
and virtual disks, and manages the RAID system. Because the utility resides in
the controller BIOS, its operation is independent of the operating systems on
your system. The BIOS Configuration Utility, also known as Ctrl+R, is built on
elements called controls. Each control performs a function. The functions
include procedures you can use to configure physical disks and virtual disks.
C
Cache
Fast memory that holds recently accessed data. Using cache speeds subsequent
access to the same data. It is most often applied to processor-memory access but
also can be used to store a copy of data accessible over a network. When data is
read from or written to main memory, a copy is also saved in cache memory with
the associated main memory address. The cache memory software monitors the
addresses of subsequent reads to see if the required data is already stored in
cache memory. If it is already in cache memory (a cache hit), it is read from
cache memory immediately and the main memory read is aborted (or not
started). If the data is not cached (a cache miss), it is fetched from main
memory and saved in cache memory.
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Glossary