Intel
®
RAID Maintenance Free Backup Unit AXXRMFBU2
User’s Guide
1
1 About the Intel
®
RAID Maintenance Free
Backup Unit AXXRMFBU2
Intel
®
Integrated RAID (Redundant Array of Inexpensive Disks) Modules provide reliability,
high performance, and fault-tolerant disk subsystem management. Acomplete fault-tolerant
strategy requires protection of all data, including the unwritten cached data in the RAM cache.
If power is lost, the data in the RAM cache is lost. To avoid data loss, a RAID Maintenance
Free Backup Unit (RMFBU) can be added to store unwritten cached data from the RAID RAM
during an AC power outage or if the AC power cord is removed.
A RAID Maintenance Free Backup Unit protects the integrity of the chached data on Intel
®
Integrated RAID Modules by offloading data stored in the RAM cache to the NAND flash if
there is a complete AC power failure or a brief power outage. The Intel
®
RAID Maintenance
Free Backup Unit provides an alternative to use an uninterruptible power supply (UPS) or it can
act as a second level of fault tolerance when used with a UPS. Furthermore, it eliminates the
need for lithium ion (Li-ion) batteries traditionally used to protect DRAM cache memory on
PCI RAID controllers. Therefore this is a greener and lower total cost cache proection solution.
The cache memory available on Intel
®
Integrated RAID Modules can improve the 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
®
Integrated RAID Module 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 is written to thte
storage device. This risk factor is eliminated when the Intel
®
Integrated RAID Module has a
RMFBU installed.
The Intel
®
RAID Maintenance Free Backup Unit AXXRMFBU2 consists of Cache Offload
Module and SuperCap2. It monitors the voltage level of the DRAM modules of the Intel
®
Integrated RAID Module. If the voltage drops below a predefined level, the RMFBU offloads
the data from the RAID RAM to the NAND flash of RMFBU2 Cache-offload Module and
SuperCap2 provides sufficient power to complete the data transferring. When the voltage level
returns to an acceptable level, the RAID RAM is recoverd from flash, and all pending writes to
storage devices are completed without losing any data.
The Intel
®
RAID Maintenance Free Backup Unit AXXRMFBU2 has built-in functionality to
charge the SuperCap2 automatically and to communicate entire unit status information such as
voltage, temperature, and current to the host server system.
The Intel
®
RAID Maintenance Free Backup Unit AXXRMFBU2 is a smart backup module and
uses MegaRAID CacheVault™ Technology. It is compatible with a backup auxiliary power
source. The SuperCap2 is charged automatically.
