Cisco UCS – BIOS settings – part 2

Basic options

Reboot on BIOS Settings change:
Always set on Enable, the maintenance policy will be in control of the needed reboot instead of the admin.

Serial port A:
Always set to Disabled, serial ports … 2016  .. not going to use it=disable!

Quiet Boot:
Always set to Disabled, I’m an admin, I want to know what’s going on = disable!

Post Error Pause:
It depends on the function of the server, usually you configure Disabled so in case of errors the server will boot up and will be operational and your monitoring tool will raise an alert.

Front Panel Lockout:
With this settings you can disable the frontpanel of a server, so the impact of physical access to a server is limited.
Usually your server is placed in a secure environment (datacenter) and there is no physical access for unauthorized people. For easier troubleshooting purposes leave this option to Disabled and secure your server by securing your server physical.

Consistent Device Naming (CDN):
CDN is a Windows Server 2012 feature were the vNIC/NIC always will appear in the same order/with the same name. So until now where Plug and Play randomly assigned a name to a (v)NIC, CDN will give a default name to a (v)NIC (even across re-installations). So, if you install Windows 2012 direct on the server you should Enabled CDN support, otherwise set the policy to Disable.

Resume AC On Power Loss:
If you lose your power in you datacenter, the last thing you want to do is to power on your server manually. Set this policy to Last State.

QuickPath Interconnect (QPI) link frequency:
In a nutshell: The QPI is the interconnect between the processors and the PCIe bus and enables non-uniform memory access (NUMA) in a multi-processor architecture, NUMA is a techonology which circumvents certain memory-access problems by providing every processor it’s own local (fast) memory. NUMA also enables a processor to access remote (slow) memory which is connected to another processor to allow a processor to all available memory. A physical processor (with multiple cores) and its connected memory modules is called a NUMA node.
Set this option to Auto: the fastest link frequency will be selected automatically.  

QuickPath Interconnect (QPI) Snoop Mode:
Current processors have multiple cores and this affects the NUMA architecture and the way L3 cache is used. Were in “old” processors every core had his own L3 cache, with new processors the L3 cache is decoupled from the core. There are just as much L3 cache dices as cores, but every core can access every L3 cache dice. This introduced a new problem were the L3 cache dices have inconsistent data. With cache coherence protocols this problem is being solved, but how this protocol work is affected by the QPI snoop mode.
I will try to explain every option:

  • Early snoop: introduced with the Sandy bridge (v1) and is available on all newer architectures. It’s delivers a low-latency cache method, but with a large amount of cores per processor there is a trade-off for the used bandwidth. This option is not ideal for NUMA optimized workloads (like vSphere), only use this option with processors with a low amount of cores (LCC) and dedicated workloads (like SQL).
  • Home snoop (HS): introduced with the Ivy Bridge (v2) and is available on all newer architectures. It has a higher latency than early snoop but with less bandwidth usage. Snooping requests are being handled central by a home agent. This mode is the recommended option for general workloads (like vSphere) and gives the overall best performance.
  • Cluster-on-Die (COD): With highly optimized NUMA workloads were VM’s fit one NUMA node you may consider Cluster-on-Die. With correctly sized workloads were the VM’s will fit one NUMA node COD will give the best performance. Only ESXi 5.5 U3 and ESXi 6.0 and later support COD, see for more information


Trusted Platform Module (TPM):
If you’ve ordered a TPM module for securing you server set it to Enabled, otherwise set the policy to Disabled.

Intel trusted Execution Technology (TXT):
This option can only be Enabled if TPM, VT and VTDio are enabled, it will give additional security.

click here for processor BIOS settings: Cisco UCS – BIOS settings – part 3

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