Change vCenter Data Center Name for 1000v

If you have changed your vCenter Data Center name and are in need of changing it in your Nexus 1000v switch, the following procedure can be followed:

From the 1000v, disconnect the VSM from vCenter:
JenN1K# conf t
JenN1K(config)# svs connection vc
JenN1K(config-svs-conn)# no connect

Change the name in the 1000v's running configuration to reflect the Data Center name change:
JenN1K(config-svs-conn)# vmware dvs datacenter-name <New name>

Reconnect the svs connection:
JenN1K(config-svs-conn)# connect

Ensure the configuration is saved in the event of a reboot or switchover:
JenN1K# copy running-config startup-config

Low Voltage CMOS Battery

The following procedure can be used in order to confirm a voltage problem alert being reported on a B-series server's CMOS battery.

The fault that will be sent is the following:
 code="F0424"
 descr="Possible loss of CMOS settings: CMOS battery voltage on server 1/1 is lower-critical"

In order to further troubleshoot this issue, the following commands can be used in order to collect
information about the CMOS battery's sensor:

 connect cimc <chassis>/<server>
 sensors

The sensor you should look for is: P3V_BAT_SCALED.
If the sensor reading is below 3.0V, a bad battery is typically the suspect.

The replacement part ID for the CMOS battery is: N20-MBLIBATT=

Circuit Trace in UCS

You may be wondering how does a packet travel from my adapter through the UCS system to the upstream switch?  The following commands can help you trace out the data path of a packet.

'show service-profile circuit server x/y' will show the VIFs associated to a particular blade:
Server: 1/1
    Fabric ID: A
        VIF        vNIC       Link State Overall Status Admin Pin  Oper Pin   Transport
        ---------- ---------- ---------- -------------- ---------- ---------- ---------
                41            Unknown    Unknown        0/0        0/0        Unknown
              9158            Up         Active         0/0        0/0        Ether
               964 eth0       Up         Active         0/0        0/3        Ether
               966 fc0        Up         Active         0/0        0/0        Fc
    Fabric ID: B
        VIF        vNIC       Link State Overall Status Admin Pin  Oper Pin   Transport
        ---------- ---------- ---------- -------------- ---------- ---------- ---------
                42            Unknown    Unknown        0/0        0/0        Unknown
              9159            Up         Active         0/0        0/0        Ether
               965 eth1       Up         Active         0/0        0/3        Ether
               967 fc1        Up         Active         0/0        0/0        Fc

Using these numbers, we can search for the active border interfaces on the system in order to determine which uplink an interface is using to reach the outside world:

'connect nxos'
'show pinning border-interfaces active'

--------------------+---------+----------------------------------------
Border Interface     Status    SIFs                                   
--------------------+---------+----------------------------------------
Po3                  Active    veth961 veth965 veth973 veth977 veth981
                               veth985 veth989 veth993 veth997  
                               veth1001 veth1005 veth1009 veth1013
                               veth1017 veth1021 veth1025 veth1029
                               veth1033 veth1037 veth1041 veth1045
                               veth1049 veth1053 veth1057 veth1061
                               veth1065 veth1069 veth1073 veth1081
                               veth1085                         

Total Interfaces : 1

We can see from the output that all traffic for virtual interfaces connected to FI B are being sent out port-channel 3.  We can take this even further and see which uplink in the port-channel has been hashed to carry the uplink traffic for a particular source.

The following command shows the hashing algorithm that will determine what uplink is used:

'show port-channel load-balance'
Port Channel Load-Balancing Configuration:
System: source-dest-ip

Port Channel Load-Balancing Addresses Used Per-Protocol:
Non-IP: source-dest-mac
IP: source-dest-ip source-dest-mac

With this in mind, the following command can be used to determine the uplink.  The source IP and destination MAC addresses are needed to complete this command:
show port-channel load-balance forwarding-path interface port-channel 3 <src ip> <dst-ip> <src-mac> <dst-mac>

In a later post, I will document how to determine the IOM backplane ports and fabric ports that a particular server is using to reach the upstream network.

The Beginning...

Hey all.  I have started this blog this morning as means for me to post information about general UCS best practices, troubleshooting tips, and any neat tricks that I think UCS administrators should know.  This blog can also be used to ask questions or post comments about a specific UCS component, topology or anything else that may be UCS-related. 

I am still working to come up with a catchy and creative name for this one-stop shop, so if you have any suggestions, let me know.