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IBM BladeCenter PS703 and PS704 Technical Overview and Introduction
Figure 4-1 shows a POWER7 chip as implemented on a PS703 or PS704 blade, with its
memory interface comprised of one controller and four advanced memory buffers. Advanced
memory buffer chips are exclusive to IBM. They help to increase performance acting as
read/write buffers. The four advanced memory buffer chips are on the system planar and
support two DIMMs each.
Figure 4-1 PS702 and PS703 memory subsystem
Memory page deallocation
Although coincident cell errors in separate memory chips are a statistical rarity, IBM POWER
processor-based systems can contain these errors using a memory page deallocation
scheme for partitions running IBM AIX and the IBM i operating systems, as well as for
memory pages owned by the POWER Hypervisor. If a memory address experiences an
uncorrectable or repeated correctable single cell error, the service processor sends the
memory page address to the POWER Hypervisor to be marked for deallocation. Pages used
by the POWER Hypervisor are deallocated as soon as the page is released.
In other cases, the POWER Hypervisor notifies the owning partition that the page should be
deallocated. Where possible, the operating system moves any data currently contained in that
memory area to another memory area and removes the page (or pages) associated with this
error from its memory map, no longer addressing these pages. The operating system
performs memory page deallocation without any user intervention and is transparent to users
and applications.
The POWER Hypervisor maintains a list of pages marked for deallocation during the current
platform IPL. During a partition IPL, the partition receives a list of all the bad pages in its
address space. In addition, if memory is dynamically added to a partition (through a dynamic
GX
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
32 MB L3 Cache
Memory Controller
SM
P Fa
b
ri
c
Port
Port
Port
Port
Memory
Buffer
Memory
Buffer
Memory
Buffer
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
POWER7
Core
256 KB L2
DDR3
DIMM
DDR3
DIMM
DDR3
DIMM
DDR3
DIMM
Memory
Buffer
Summary of Contents for BladeCenter PS703
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