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A more detailed description and the exact sequence for installation is provided in
the IBM: System x3850 M2 and x3950 M2 Installation Guide, available from:
http://www.ibm.com/support/docview.wss?uid=psg1MIGR-5073028
If you want to install the full 256 GB, remove the existing DIMMs and fully
populate the x3850 M2 and x3950 M2 with four memory cards, each with 8 GB
DIMMs.
3.2.3 Memory mirroring
Memory mirroring is available on the x3850 M2 and x3950 M2 for increased fault
tolerance. Memory mirroring is operating system-independent, because all
mirroring activities are handled by the hardware. This setting can be changed as
described in section 3.2.6, "Memory configuration in BIOS" on page 121.
The x3850 M2 and x3950 M2 have four separate memory power buses that each
power one of the four memory cards. Figure 3-12 on page 113 shows the
location of the memory cards, which are numbered 1 to 4, from left to right. The
DIMM sockets and Memory card LEDs are shown in Figure 3-14 on page 116.
Mirroring takes place across two memory cards, as follows:
The memory DIMMs in card 1 are mirrored to the memory DIMMs in card 2.
The memory DIMMs in card 3 are mirrored to the memory DIMMs in card 4.
Therefore, with memory mirroring enabled in the BIOS, you can hot-swap any
memory card if the hot-swap enabled LED is lit. For instructions to hot-swap a
memory card, see IBM: System x3850 M2 and System x3950 M2 User's Guide:
http://www.ibm.com/support/docview.wss?uid=psg1MIGR-5073029
After memory-mirroring is enabled, the data that is written to memory is stored in
two locations. For read operations, data is read from the DIMMs with the least
amount of reported memory errors reported through memory scrubbing.
Table 3-8 shows the possible BIOS settings for the initialization of scrub control.
The setting is accessed by going to (from the system startup Main Menu)
Advanced Setup → Memory Settings → Initialization Scrub Control.
Table 3-8 Initialization scrub control
Setting
Scrub on Every Boot
Scrub only after AC Cycle
118
Planning, Installing, and Managing the IBM System x3950 M2
Function
Performs full memory test on every boot
Performs scrub only after AC has been removed or applied
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