Bandwidth And Performance; Memory Mirroring And Ras - Cisco UCS B200 Installation And Service Note

Removing a Blade Server Cover
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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Bandwidth and Performance

Recommendations for achieving performance of 1333 MHz on B200 M1 servers:
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Recommendations for achieving performance of 1333 MHz on B200 M2 servers:
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Performance Degradation
Performance degradation can occur if the following memory configurations are used:
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Memory Mirroring and RAS

The Intel Nehalem–EP CPUs within the blade server support memory mirroring only when no more than
two Channels are populated with DIMMs. If three Channels are populated with DIMMs, memory
mirroring is automatically disabled. Furthermore, if memory mirroring is used, DRAM size is reduced
by 50% for reasons of reliability.
If the RAS (Reliability, Availability, and Serviceability) option is required, it is available only when
Channel–3 is not populated.
Cisco UCS B200 Blade Server Installation and Service Note
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DIMMs can be run in a 1 DIMM per–Channel or a two DIMM per–channel configuration. Each of
these arrangements can provide different behavior.
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
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 logical bank or 2 logical 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.
Use Intel Xeon X5680, X5670, or X5650 processors (see
Use only Cisco certified single or dual rank DIMMs that support 1333 MHz speeds (see
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.
Mixing DIMM sizes and densities within a channel
Partially populating a channel
Unevenly populating DIMMs between CPUs
Table 4).
Table 3).
Table 6).
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