NEC Express5800/110Ge, User Manual, Page: 242 / 332

9-32 Upgrading Your Server
Maximum Memory Capacity
The available memory capacity depends on the basic architecture of the server (x86 architecture)
and specifications of supported operating systems.
„
Memory hole
– The x86 architecture (IA-32) adopts Memory Mapped I/O method which reserves the
fixed memory area (memory hole) for controlling various I/O devices (e.g., onboard
device and PCI devices).
– The memory hole reserves 4GB or less physical memory area as reserved memory area,
regardless of mounted memory capcity. The OS cannot access this reserved area, thus,
the available memory capacity may be less than the actual mounted memory capacity
due to the memory hole.
„
Memory Reclaim feature
– The server provides Memory Reclaim feature for complementation of memory hole.
– The Memory Rclaim feature remaps physical memory addresses in the memory hole on
hardware (chipset). By remapping, the whole capacity of mounted memory can be
used.
– Note, however, the remap memory area may not be avaiable depending on the memory
capacity supported by OS. Accordingly, the available memory capacity depends on the
supported OS.
Memory hole
(with physical 4GB memory installed) Memory Reclaim feature
(with physical 4GB memory installed)
Note: When the OS support memory can support the
total capacity of physical memory and memory
hole.
Memory
hole
Memory capacity
available for OS:
Approx. 3.3GB
Memory capacity
unavailable for
OS: (Approx.
700MB)
Physical
memory:
4GB
Physical
memory
Physical
memory:
0GB
Memory
hole
Remap
memory
Memory capacity
unavailable for OS:
(Approx. 700MB)
Memory capacity
available for OS:
Approx. 3.3GB
Physical
memory
Physical
memory:
0GB
Physical
memory:
4GB
Remaps physical
memory in the memory
hole on hardware.
The OS can use whole
physical memory
mounted.