HP Surestore Disk Array 12h and FC60 - Manual (Page 40)

40 Array Controller Enclosure Components
Controller Memory Modules
Each controller module contains SIMM and DIMM memory modules. Two 16-Mbyte SIMMs
(32 Mbytes total) store controller program and other data required for operation. The
standard controller module includes 256-Mbytes of cache DIMM, which is upgradeable to
512 Mbytes. The cache may be configured as either two 128-Mbyte DIMMs, or a single 256-
Mbyte DIMM. Cache memory serves as temporary data storage during read and write
operations, improving I/O performance. When cache memory contains write data, the Fast
Write Cache LED, on the front of the controller enclosure is on. See
Figure 13 .
Controller Fan Modules
The controller fan module is a single removable unit containing dual cooling fans and
temperature monitoring logic. See
Figure 13 . It includes five LEDs that indicate overall
system status and controller fan status. The fans provide cooling by pulling air in through
ventilation holes, moving it across the controller cards, and exhausting it out the
ventilation holes in the fan assembly. The dual fans provide a redundant cooling system to
both controller modules. If one fan fails, the other continues to operate and provide
sufficient air circulation to prevent the controllers from overheating until the fan module is
replaced. The fan module plugs into a slot on the front of the controller enclosure, and has
a handle and captive screw for easy service.