Troubleshooting the sensor

Host Signature error occurs on Red Hat Enterprise Linux 7 and CentOS Linux 7 targets

Problem

When you discover target systems that run Red Hat Enterprise Linux 7, or CentOS Linux 7, the following error occurs:

2016-03-31 15:46:31,759 DiscoverManager [DiscoverWorker-7]               
SessionSensor-9.1.146.78-[22] DEBUG session.SshSessionClient - Command   
[LC_ALL=en_US.UTF-8;LANG=en_US.UTF-8;export LANG LC_ALL;ifconfig  -a]    
failed in session                                                        
ssh2:/HostAuthcom.collation.platform.security.auth.HostAuth[asmcfm][XX 
XXX]/null@9.1.146.78: exit status 127 (no stdout)

Solution

To solve the problem, you must install the ifconfig command on the targets, or choose any other command that can manage network interfaces. You must specify its name and path in the com.collation.platform.os.command.ifconfig property in the collation.properties file. For details, see Configuring the collation.properties file entries.

The sensor fails with a command failed to run error

Problem

The following message is displayed:

Error Message: CTJTD0431E: The following command failed to run or returns 
a blank value: sudo /sbin/vmcp q userid | awk 'print{3}'.

The command vmcp q userid has failed to run or returns a blank value on the target Linux virtual system running on a z/VM® operating system.

Solution

This problem is caused by one of the following conditions:

• An incorrect path for the vmcp command on the target Linux virtual system.
• The vmcp tool is not installed on the target Linux virtual system.
• The sudo command is not configured to run the vmcp command.
• The system name is not configured on the z/VM system.

To solve this problem, complete the following steps:

• Verify that the correct path for the vmcp command is entered in the collation.properties file. For details, see Configuring the collation.properties file entries.
• Verify that the system name is configured on the z/VM system, the system name cannot be blank.
• If the vmcp tool is not installed on the Linux virtual system, you must load it. To load the vmcp device driver, issue the modprobe vmcp command on the Linux guest.
• Verify that the sudo command is available. To verify run the following command on the Linux guest where the monitoring agent is installed:

  sudo vmcp q userid

  If sudo is active and loaded, this command sends the q userid command to the hosting virtual machine, which queries the user ID for the guest.
  If there is not a requirement to reconcile the Linux virtual system to the host system on the z/VM operating system, it is not necessary to run the vmcp command. You can use the externalized command property (com.collation.discover.agent.command.vmcp.Linux=) in the collation.properties file to set the host system value to a dummy value. You must be able to parse the externalized command with the following command appended to it:

  q userid | awk '{ print $3 }'

  For example, you might use:

  com.collation.discover.agent.command.vmcp.Linux.192.168.1.2=echo A B zVMHost

  This produces the echo A B zVMHost q userid | awk '{print $3 }' which returns the zVMHost name. The host attribute for your virtual systems is set to zVMHost instead of the actual host system name.
• You can disable the vmcp command by setting the ignoreVMCPCommand command to true. For instructions, see Configuring the collation.properties file entries.

z/VM guests can be duplicated after multiple discoveries of the same Linux virtual system

Problem

Duplicates can occur if the command vmcp q userid returns a blank value on the target Linux virtual system running on a z/VM operating system.

Solution

You must manually merge these duplicates.

Linux Computer System Sensor captured memory size is inaccurate.

Problem

When discovering Linux computer systems, the memory size captured by the sensor does not match with the installed memory size.

Solution

The solution is to enable dmidecode, as it gives the most accurate value of installed memory.