Troubleshooting guide

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Cisco UCS B22 Blade Server Installation and Service Note
OL-27513 -01
Removing a Blade Server Cover
Bandwidth and Performance
Recommendations for achieving performance of 1600 MHz on B22 M3 servers:
• Ensure that both the installed CPU and the selected DIMMs support operation at 1600 MHz. If either
cannot support this, the pair will run at the highest speeed of the slower of the two.
• Ensure the server is running the 2.0(2) or later BIOS version. If a BIOS upgrade is needed, do it
before installing processors or memory.
• Use only Cisco certified DIMMs that support 1600 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
1600 MHz.
• Fully populating 1 logical bank or 2 logical banks with DIMMs will ensure optimal memory
bandwidth running at the 1600 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 1600 MHz speed can be
used, but the overall memory bandwidth will not be optimal.
Performance Degradation
Performance degradation can occur if the following memory configurations are used:
• Mixing DIMM sizes and densities within a channel
• Partially populating a channel
• Unevenly populating DIMMs between CPUs
Memory Mirroring and RAS
The Intel 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.
Installing a Modular LOM
The modular LOM is a specialized I/O adapter providing 2 x 10 Gigabit of Ethernet/FCoE connectivity
to each chassis IOM. The following option is available:
Table 6 Modular LOM Options
Cisco Product ID Name
UCSB-MLOM-40G-01 Cisco VIC 1240 - 40 Gb mLOM for UCS M3 Blade Servers. Plugs
into the dedicated mLOM connector only. It is the only card that can
be plugged into the mLOM connector.