Chapter 6. Troubleshooting

6.1. Debug Logging

By default, virt-who logs all its activity to the file /var/log/rhsm/rhsm.log. When troubleshooting, check the log file as this may reveal useful information. To enable more detailed logging, change the debugging line in the global configuration file /etc/sysconfig/virt-who to VIRTWHO_DEBUG=1. If virt-who is running as a service, you must restart it for the configuration change to take effect. When you have resolved the underlying issue, disable diagnostic logging by changing the debugging line back to VIRTWHO_DEBUG=0 and restarting the virt-who service.

6.2. Duplicate Configuration Lines

Since there can be multiple configuration files, both global and hypervisor-specific, duplicate configuration lines may result in virt-who behaving differently to what you intend.

To detect duplicate lines in the virt-who configuration files, use the following command. The output of this command is a list of all lines in the specified files, prefixed by the number of times it occurs. Check all instances where the same line is listed as occurring twice or more, remove the duplicate line and restart the virt-who service. For instructions see Section 5.7.1, “Restarting the virt-who Service”. 

cat /etc/sysconfig/virt-who /etc/virt-who.d/* | sort | uniq -c

6.3. Credentials

Incorrect credentials can be a source of virt-who failure. If possible, test the credentials configured for use by virt-who by logging in to the virtualization hypervisor. For example, if you can log in to the VMware vSphere management console and the expected hosts are visible, then credentials are correct.

6.4. Testing Configuration Options

When troubleshooting, a common method of determining the root cause of a problem is to make a change and test the result, repeating as needed. The virt-who agent provides an option to help with this technique.

Run the command virt-who --one-shot which reads all configuration files, retrieves the list of virtual machines from all sources, then exits immediately. This tests the configuration files, credentials and connectivity to configured virtualization platforms. 

# virt-who --one-shot

The output you can expect is a list of hypervisors and the hosted guest virtual machines, in JSON format. The following is an extract from virt-who output from a VMware vSphere instance. The output from all hypervisors follows the same structure. 

{
    "guestId": "422f24ed-71f1-8ddf-de53-86da7900df12",
    "state": 5,
    "attributes": {
        "active": 0,
        "virtWhoType": "esx",
        "hypervisorType": "vmware"
    }
},

6.5. Example Scenarios

6.5.1. Virt-who fails to connect with the virtualization platform

Check the Red Hat Subscription Manager log file - /var/log/rhsm/rhsm.log - if virt-who fails to connect with the virtualization platform. If you find the message No route to host, one possible reason is that the hypervisor is listening on a port other than what you expect. For example, Red Hat Virtualization Manager defaults to port 8443 for backward compatibility, but virt-who defaults to using port 443. In this case, you would edit the hypervisor’s configuration file in /etc/virt-who.d/ and append :443 to the value for the server line, resulting in the line: server=https://rhevmhost1.example.com:443.