Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 349

Appendix B Glossary access policy alarm enabled alarm present array BBU present BGI rate BIOS cache A virtual drive property indicating what kind of access is allowed for a particular virtual drive. The possible values are Read/Write, Read Only, or Blocked. A controller property that indicates whether the controller's onboard alarm is enabled. A controller property that indicates whether the controller has an onboard alarm. If present and enabled, the alarm is sounded for certain error conditions. See drive group. A controller property that indicates whether the controller has an onboard battery backup unit to provide power in case of a power failure. A controller property indicating the rate at which the background initialization of virtual drives will be carried out. Basic Input/Output System. The computer BIOS is stored on a flash memory chip. The BIOS controls communications between the microprocessor and peripheral devices, such as the keyboard and the video controller, and miscellaneous functions, such as system messages. Fast memory that holds recently accessed data. Use of cache memory speeds subsequent access to the same data. 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. MegaRAID SAS Software User Guide B-1