BROADCOM CVPM05

Cache Backup Benefits
The cache memory available on MegaRAID controllers improves overall system performance because writing data to the
controller’s cache memory is much faster than writing it to a storage device. Write operations appear to complete quickly
at the software application level. The MegaRAID controller writes the cached data to the storage device when system
activity is low or when the cache gets full.
The risk of using write-back cache is that the cached data can be lost if the AC power fails before the data is written to the
storage device. To eliminate this risk, the MegaRAID controller supports an energy backup solution to ensure no data is
lost during power or system failure. The cached data is offloaded to flash, which is restored when power resumes.
CacheVault Modules
CacheVault technology consists of two primary items. The CVPM is an ultracapacitor-based energy source that powers
the critical adapter components in the event of a power loss, long enough to offload cached data to the nonvolatile flash
memory on the CVFM. The DRAM contents are restored to the CVFM the next time the MegaRAID controller is powered,
and the cached data is written to the storage devices. The CVPM is also sometimes referred to as a supercapacitor or
flash backup unit (FBU).
CacheVault flash technology virtually eliminates the hardware maintenance associated with batteries, offers lower total
cost of ownership over the life of the controller, and provides more environmentally friendly cache protection, all while
maintaining optimal RAID performance.
The following table describes the cache protection options for each MegaRAID adapter.