Sun Oracle Fire X4470 M2, Service Manual

Page: 60 / 194

4-6 Sun Server X2-4 Service Manual • April 2013
2. Provide DIMMs on every DRAM channel (at least 4 DIMMs per memory riser).
3. For each CPU, have equal total gigabytes on the MR0 and MR1 risers. Memory
bandwidth is 5% higher when all pairs of risers have balanced capacity.
4. Spread the memory capacity evenly across the CPUs so the operating system can
distribute large memory tasks better.
5. Avoid mixing dual-rank and quad-rank DIMMs in the same memory riser.
4.1.4.1 Recommended Memory Placement
For the Sun Server X2-4, the operating speed of the DIMMs does not decrease as
more DIMMs are installed. For best memory performance, follow these simple
guidelines to add or replace DIMMs in the server. Use one or more sizes of DIMMs,
with an even number of DIMMs of each size.
1. Using the largest-capacity DIMMs, add two DIMMs per riser, starting at P0/MR0,
continuing through P3/MR1, and then beginning again at P0/MR0 if necessary,
until all of the largest-capacity DIMMs are placed.
For installations with one DIMM size, all DIMMs will be placed in this step. For
installations with additional DIMMs of different sizes, continue to the next
guideline step.
If you are adding or replacing quad-rank (16GB) DIMMs, they can be installed
only in D0/D4 slots or D2/D6 slots, or else in DRAM channels where those slots
already contain 16GB DIMMs.
2. Using DIMMs of the next largest capacity, add two DIMMs per riser, starting with
risers with the fewest DIMMs and proceeding from P0/MR0, continuing through
P3/MR1, and then beginning again at P0/MR0 if necessary, until there are no
more DIMMs of this size, or all risers have four DIMMs.
As long as any riser has fewer than four DIMMs, keep repeating this step with the
DIMMs of decreasing capacity. When all risers have four DIMMs, continue to the
next guideline step.
3. Using DIMMs of the next largest capacity, add two DIMMs per riser to risers with
the least total gigabytes. Start from P0/MR0, continuing through P3/MR1, and
then begin again at P0/MR0 is necessary.
Repeat guideline step 3 with all remaining DIMMs, in decreasing order of DIMM
capacity, until all DIMMs are placed.