IBM x3690 X5 Service Manual page 316

v The server system board provides four memory ports (memory channels) for
v The following table shows the DIMM connectors on the system board and the
v When you replace a DIMM, the server provides automatic DIMM enablement
v DIMMs must be installed in matched pairs (non-mirroring mode) or matched
v A minimum of two DIMMs must be installed for each microprocessor. For
v The maximum operating speed of the server is determined by the slowest
v The server comes with a minimum of two DIMMs installed in slots 1 and 8.
v The server support memory sparing. Memory sparing reserves memory capacity
v The server supports non-mirroring mode and memory-mirroring mode.
v Non-mirroring mode. When you use the non-mirroring mode, install DIMMs as
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System x3690 X5 Types 7147, 7148, 7149, and 7192: Problem Determination and Service Guide
each microprocessor and each memory port supports up to four DIMMs. The
optional memory tray also provides four memory ports that supports up to four
DIMMs per memory port.
memory tray that are associated with each microprocessor when the memory
tray is also installed in the server:
Table 18. DIMM connectors associated with each microprocessor
Microprocessor
Microprocessor socket 1
Microprocessor socket 2
Note: When the memory tray is not installed in the server, DIMMs 1 through 16
are solely associated with microprocessor 1. Microprocessor 2 has access to
DIMMs 1 through 16, but access is through microprocessor 1. This is important
if load balancing is a necessity for your operating system or software load.
capability without you having to go to Setup to enable the new DIMM
manually.
sets of four (memory mirroring mode).
example, you must install a minimum of four DIMMs if the server has two
microprocessors installed. However, to improve system performance, install a
minimum of four DIMMs for each microprocessor.
DIMM installed in the server.
When you install additional DIMMs, install them in the order shown in the
following information in the non-mirroring mode and mirroring mode tables to
optimize system performance.
for failover in the event of a DIMM failure, and the reserved capacity is
subtracted from the total available memory. Memory sparing provides less
redundancy than memory mirroring does. If a predetermined threshold of
correctable errors is reached, the contents of the failing DIMM are copied to the
spare memory, and the failing DIMM or rank is disabled. To enable memory
sparing through the Setup utility, select System Settings > Memory.
indicated in the following tables.
– The following table lists the DIMM installation sequence for non-mirroring
mode when one or two microprocessors and no memory tray installed in the
server:
Table 19. non--mirroring mode (normal) DIMM population sequence when one or two
microprocessors and no memory tray is installed
Pairs of DIMMs
Pair 1
DIMM connectors
1 through 16
17 through 32
Number of installed
microprocessors
1 or 2
DIMM connector
population sequence with
no memory tray
1, 8