IBM BladeCenter HS23, Installation And User Manual, Page: 40 / 98

Table 2. Memory channel configuration
Memory channel
DIMM connector
(microprocessor 1) DIMM connector
(microprocessor 2)
Channel 0 7 and 8 15 and 16
Channel 1 1 and 2 13 and 14
Channel 2 3 and 4 9 and 10
Channel 3 5 and 6 11 and 12
Depending on the memory mode that is set in the Setup utility, the blade server
can support a minimum of 4 GB and a maximum of 128 GB of system memory on
the system board in a blade server with one microprocessor. If two microprocessors
are installed, the blade server can support a minimum of 8 GB and a maximum of
256 GB of system memory. There are four different memory modes:
v Independent channel mode: Independent channel mode gives a maximum of
128 GB of usable memory with one microprocessor installed, and 256 GB of
usable memory with two microprocessors installed (using 16 GB DIMMs). The
DIMMs can be installed without matching sizes. See the table below for the
memory installation order.
v
Rank sparing mode: In rank sparing mode, one rank of a DIMM in each
populated channel is reserved as spare memory. The spare rank is not available
as active memory. When the active rank memory fails, its content is copied to
the spare rank memory which becomes active. The memory set aside for spare is
one rank per channel. The size of a rank varies depending on the DIMMs
installed. The DIMM population ordering for rank sparing mode is the same as
that for independent channel mode.
Table 3. DIMM population sequence for independent-channel mode and rank-sparing mode
One microprocessor installed Two microprocessors installed
DIMM connectors 1, 7, 3, 5, 2, 8, 4, and 6 DIMM connectors 1, 16, 7, 14, 3, 9, 5, 11, 2,
15, 8, 13, 4, 10, 6, and 12
v Mirrored channel mode: In mirrored channel mode, the memory contents on
channel 0 are duplicated in channel 2, and the memory contents of channel 1 are
duplicated in channel 3. The effective memory available to the system is only
half of that installed. The maximum available memory (with 16 GB DIMMs) is
64 GB for a single microprocessor system and 128 GB for a dual microprocessor
system.
Important: The memory configuration of channel 0 must match that of channel
2, and the memory configuration of channel 1 must match that of channel 3. For
example, if a 4 GB Dual Rank DIMM is installed into the DIMM connector 3
(channel 0), then a 4 GB Dual Rank DIMM must also be installed into the DIMM
connector 7 (channel 2). Table 2 lists each channel and which DIMM connectors
belong to the channel.
The following table shows the order that memory DIMMs are installed to use a
mirrored channel mode.
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BladeCenter HS23 Types 7875 and 1929: Installation and User's Guide