Broadcom CVFM04, User Manual

Page: 4 / 22

CVPM02, CVPM05, CVFM04 User Guide CVPM02, CVPM05 Power Modules | CVFM04 Cache Module
Introduction
This guide documents the following Broadcom
®
MegaRAID
®
cache backup products used with MegaRAID SAS high-
performance SAS+SATA RAID controllers to protect cached data:
•
CacheVault
™
flash module (CVFM)
–
CVFM04
•
CacheVault power modules (CVPMs)
–
CVPM02
–
CVPM05
The memory modules protect the integrity of cached data on MegaRAID controllers by offloading the cached data to
nonvolatile flash memory if a complete AC power failure, or a brief power outage, occurs. These products provide an
alternative to using an uninterruptible power supply (UPS), or a second level of fault tolerance when used with a UPS.
This guide describes the backup products, including installation instructions and technical specifications.
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.
Table 1: MegaRAID CacheVault Flash Modules Matrix
MegaRAID
Adapter
Adapter
Controller CacheVault Kit
CacheVault
Memory Module
Module Information
CacheVault
Power Module
9560-16i
9560-8i
9580-8i8e SAS3916
or
SAS3908
— NAND flash is local on
adapter.
Separate flash module not required.
The CVPM or supercapacitor provides
the CacheVault technology.
CVPM05 (FBU345)
Broadcom CVPM02-05-CVFM04-UG101
4