Cache Memory - HP XP7 Owner's Manual

Figure 15 Disk chassis (fan door open)
As shown in Figure 15 (page 59), the fan assemblies on both the front and rear sides of the drive
chassis fold out and away from the unit to allow access to the disk drives. The three speed fans in
the drive chassis are thermostatically controlled by a temperature sensor (thermistor) in the unit.
The sensor measures the temperature of the exhaust air from the unit and sets the fan speed as
needed to maintain the unit temperature within a preset range. When the unit is not busy and cools
down, the fan speed is reduced, saving energy and reducing the noise level of the unit.
When the fan assemblies are opened, the power to the fans is automatically switched off and the
fans stop rotating. This helps prevent possible injury because there is no protective screen on the
back side of the fans.

Cache memory

The HP XP7 can be configured with up to 512 GB of cache memory per controller chassis (1024
GB for a two-module system). The cache is nonvolatile and is protected from data loss with onboard
batteries to backup cache data into the onboard Cache Backup Memory Solid States Disk drive.
Each controller chassis can contain from two to eight cache memory adapter boards. Each board
contains from 8 GB to 64 GB.
Cache memory adaptor boards are installed in pairs and work together to provide cache and
shared memory for the system. In addition to the memory on the cache boards, 4 GB of cache
memory is also located on each Micro Processor Blade board. See the following illustration.
Cache memory 59