HP P2000 G3 MSA Array Systems - Manual (Page 22)

22 Components
CAUTION: To preserve the existing data stored in the CompactFlash, you must transport the
CompactFlash from the failed controller to the replacement controller using a procedure outlined in the HP
Controller Module Replacement Instructions, shipped with the replacement controller. Failure to use this
procedure will result in the loss of data stored in the cache module. The CompactFlash must stay with the
same enclosure. If the CompactFlash is used/installed in a different enclosure, data loss/data corruption
will occur.
IMPORTANT: In dual controller configurations featuring one healthy peer controller, there is no need to
transport a failed controller’s cache to a replacement controller because the cache is duplicated between
the controllers.
Super-capacitor pack
To protect RAID controller cache in case of power failure, P2000 G3 MSA System controllers are equipped
with super-capacitor technology, in conjunction with CompactFlash memory, built into each controller
module to provide unlimited cache memory backup time. The super-capacitor pack provides energy for
backing up unwritten data in the write cache to the CompactFlash in the event of a power failure. Unwritten
data in CompactFlash memory are automatically committed to disk media when power is restored. While
the cache is being maintained by the super-capacitor, the Cache Status LED flashes at a rate of 1/10
second on and 9/10 second off.