S e n d d o c u m e n t c o m m e n t s t o u c s - d o c f e e d b a c k @ c i s c o . c o m
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Cisco UCS B250 Extended Memory Blade Server Installation and Service Note
OL-22474-03
Memory and Performance
•
DIMMs can be run in a 2 DIMM per–Channel, 4 DIMM per–Channel, or an 8 DIMM per–channel
configuration. Each arrangement can provide different behavior.
Bandwidth and Performance
You can achieve maximum bandwidth, performance, and system memory using the following
configuration:
Note
M1 models are optimized at 1066 MT/s DDR3 operation. M2 models support 1333 MT/s DDR3
operation when running with a memory voltage of 1.5V, given CPUs supporting this speed; and
1066MT/s DDR operation when running in LV mode, given CPUs and DIMMs supporting this
configuration.
•
8 DIMM per–Channel (48 DIMMs)
•
Maximum capacity of 384 GB (using 8-GB DIMMs)
Recommendations for achieving performance of 1333 MHz on B250 M1 servers:
•
Ensure the server is running the 1.3(1) or later BIOS version. If a BIOS upgrade is needed, do it
before installing processors or memory.
•
Use Intel Xeon X5570 or X5550 processors (PIDs N20-X00001 and N20-X00006).
•
Use only Cisco certified single or dual rank DIMMs that support 1333 MHz speeds (see
Table 3
).
DIMMs do not have to be identical in type or capacity, but beware of the caveats listed in the section
below regarding performance degradation.
•
Always set the system BIOS to operate the DIMMs in "Performance" mode in order to run at
1333 MHz.
•
Fully populating 1 bank or 2 banks with DIMMs will ensure optimal memory bandwidth running at
the 1333 MHz speed. If DIMMs are partially populated in 1 bank (less than 6 DIMMs) or 2 bank
patterns (less than 12 but greater than 6 DIMMs) the 1333 MHz speed can be used, but the overall
memory bandwidth will not be optimal.
Recommendations for achieving performance of 1333 MHz on B250 M2 servers:
•
Use Intel Xeon X5680, X5670, or X5650 processors (see
Table 4
).
•
Use only Cisco certified single or dual rank DIMMs that support 1333 MHz speeds (see
Table 6
).
DIMMs do not have to be identical in type or capacity, but beware of the caveats listed in the section
below regarding performance degradation.
•
Always set the system BIOS to operate the DIMMs in "Performance" mode in order to run at
1333 MHz.
•
Fully populating 1 bank or 2 banks with DIMMs will ensure optimal memory bandwidth running at
the 1333 MHz speed. If DIMMs are partially populated in 1 bank (less than 6 DIMMs) or 2 bank
patterns (less than 12 but greater than 6 DIMMs) the 1333 MHz speed can be used, but the overall
memory bandwidth will not be optimal.
Performance Loss
Performance will be less than optimal if you unevenly populate DIMMs between CPUs. Depending on
the application needed, performance loss might or might not be noticeable or measurable.
