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APPENDIX
vides an additional level of protection. In the event of a power
failure, a BBM supplies power to retain data in the RAID con-
troller’s cache, thereby permitting any potentially dirty data in
the cache to be flushed out to secondary storage when power
is restored.
The batteries in the BBM are recharged continuously through
a trickle-charging process whenever the system power is on.
The batteries protect data in a failed server for up to three
or four days, depending on the size of the memory module.
Under normal operating conditions, the batteries last for three
years before replacement is necessary.
• Recovery ROM
RAID controller firmware is stored on the flash ROM and is ex-
ecuted by the I/O processor. The firmware can also be updat-
ed through the RAID controllers Thunderbolt port or Ethernet
port without the need to replace any hardware chips. During
the controller firmware upgrade flash process, it is possible
for a problem to occur resulting in corruption of the controller
firmware. With our Redundant Flash Image feature, the con-
troller will revert back to the last known version of firmware
and continue operating. This reduces the risk of system failure
due to firmware crash.
