IBM 88553RX, Installation Manual

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14
IBM
Eserver
xSeries 455 Planning and Installation Guide
System memory
DIMMs must be installed in matched pairs, since the DIMMs are two-way
interleaved. However, if memory is installed in matched fours (a matched pair in
each port), the system automatically detects this and will enable 4-way
interleaving. With this, memory access is performed simultaneously from both
ports (two separate paths into the memory controller as shown in Figure 1-4 on
page 8), leading to improved memory performance.
Figure 1-8 Memory DIMMs are divided into two ports
There are a number of advanced features implemented in the x455 memory
subsystem, collectively known as
Active Memory
:
Memory ProteXion
Memory ProteXion, also known as “redundant bit steering”, is the technology
behind using redundant bits in a data packet to provide backup in the event of
a DIMM failure.
Port 1 Port 2
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