Troubleshoot Workload Balancing

While Workload Balancing usually runs smoothly, this series of sections provides guidance in case you encounter issues.

Notes:

  • Workload Balancing is available for Citrix Hypervisor Premium Edition customers or those customers who have access to Citrix Hypervisor through their Citrix Virtual Apps and Desktops entitlement. For more information about Citrix Hypervisor licensing, see Licensing. To upgrade, or to buy a Citrix Hypervisor license, visit the Citrix website.
  • Workload Balancing 8.2 is compatible with XenServer 7.1 CU2 and Citrix Hypervisor 8.2.
  • To run the latest version of the Workload Balancing virtual appliance on a XenServer 7.1 CU2 host, install Hotfix XS71ECU2040 on the XenServer 7.1 CU2 host. This hotfix enables you to use all Workload Balancing features.

Determine the status of the Workload Balancing virtual appliance

Run the service workloadbalancing status command. For more information, see Workload Balancing commands.

General troubleshooting tips

  • Start troubleshooting by reviewing the Workload Balancing log files (LogFile.log and wlb_install_log.log). You can find these logs in Workload Balancing virtual appliance in this location (by default):

    /var/log/wlb

    The level of detail in these log files can be configured by using the wlb.conf file. For more information, see Increase the detail in the Workload Balancing log.

  • Check the logs in the XenCenter Logs tab for further information.

  • To check the Workload Balancing virtual appliance build number, run the following command on a host in a pool that the VPX monitors:

     xe pool-retrieve-wlb-diagnostics | more
    

    The Workload Balancing version number appears at the top of the output.

  • The Workload Balancing virtual appliance is based on the CentOS operating system. If you experience CPU, memory, or disk related issues in the virtual appliance, you can use the standard Linux logs in /var/log/* to analyse the issue.

  • Use standard Linux debugging and performance tuning commands to understand the virtual appliance behavior. For example, top, ps, free, sar, and netstat.

Error messages

Workload Balancing displays errors on screen as dialog boxes and as error messages in the Logs tab in XenCenter.

If an error message appears, review the XenCenter event log for additional information. For more information, see the XenCenter product documentation.

Issues entering Workload Balancing credentials

If you cannot successfully enter the virtual appliance user account and password while configuring the Connect to WLB Server dialog, try the following:

  • Ensure that Workload Balancing virtual appliance imported and was configured correctly and all of its services are running.

  • Check to ensure that you are entering the correct credentials. The Connect to WLB Server dialog asks for two different credentials:

    • WLB Server Credentials: Citrix Hypervisor uses this account to communicate with Workload Balancing. You created this account on the Workload Balancing virtual appliance during Workload Balancing Configuration. By default, the user name for this account is wlbuser.
    • Citrix Hypervisor Credentials: This account is used by the Workload Balancing virtual appliance to connect to the Citrix Hypervisor pool. This account is created on the Citrix Hypervisor pool master and has the pool-admin or pool-operator role.
  • You can enter a host name in the Address box, but it must be the fully qualified domain name (FQDN) of the Workload Balancing virtual appliance. Do not enter the host name of the physical server hosting the appliance. If you are having trouble entering a computer name, try using the Workload Balancing appliance’s IP address instead.

  • Verify that the host is using the correct DNS server and the Citrix Hypervisor server can contact Workload Balancing server using its FQDN. To do this check, ping the Workload Balancing appliance using its FQDN from the Citrix Hypervisor server. For example, enter the following in the Citrix Hypervisor server console:

     ping wlb-vpx-1.mydomain.net
    

Issues with firewalls

The following error appears if the Workload Balancing virtual appliance is behind a hardware firewall, and you did not configure the appropriate firewall settings: “There was an error connecting to the Workload Balancing server: <pool name> Click Initialize WLB to reinitialize the connection settings.” This error might also appear if the Workload Balancing appliance is otherwise unreachable.

If the Workload Balancing virtual appliance is behind a firewall, open port 8012.

Likewise, the port Citrix Hypervisor uses to contact Workload Balancing (8012 by default), must match the port number specified when you ran the Workload Balancing Configuration wizard.

Lose the connection to Workload Balancing

If you receive a connection error after configuring and connecting to Workload Balancing, the credentials might no longer be valid. To isolate this issue, try:

  • Verifying the credentials you entered in the Connect to WLB Server dialog box match the credentials:

    • WLB Server Credentials: Citrix Hypervisor uses this account to communicate with Workload Balancing. You created this account on the Workload Balancing virtual appliance during Workload Balancing Configuration. By default, the user name for this account is wlbuser.
    • Citrix Hypervisor Credentials: This account is used by the Workload Balancing virtual appliance to connect to the Citrix Hypervisor pool. This account is created on the Citrix Hypervisor pool master and has the pool-admin or pool-operator role.
  • Verifying the IP address or FQDN for the Workload Balancing virtual appliance that you entered in the Connect to WLB Server dialog box is correct.

  • Verifying the user name you created during Workload Balancing Configuration matches the credentials you entered in the Connect to WLB Server dialog box.

Workload Balancing connection errors

If you receive a connection error in the Workload Balancing Status line on the WLB tab, you might need to reconfigure Workload Balancing on that pool.

Click the Connect button on the WLB tab and reenter the server credentials.

For more information, see CTX231579 - Troubleshooting Workload Balancing (WLB) issues when connecting via XenCenter.

Workload Balancing stops working

If Workload Balancing doesn’t work (for example, it doesn’t let you save changes to settings), check the Workload Balancing log file for the following error message:

dwmdatacolsvc.exe: Don't have a valid pool. Trying again in 10 minutes.

This error typically occurs in pools that have one or more problematic VMs. When VMs are problematic, you might see the following behavior:

  • Windows. The Windows VM crashes due to a stop error (“blue screen”).
  • Linux. The Linux VM might be unresponsive in the console and typically does not shut down.

To work around this issue:

  1. Force the VM to shut down. To do so, you can do one of the following on the host with the problematic VM:

    • In XenCenter, select the VM, and then from the VM menu, click Force Shutdown.

    • Run the vm-shutdown xe command with the force parameter set to true. For example:

       xe vm-shutdown  force=true  uuid=vm_uuid
      

      You can find the host UUID on the General tab for that host (in XenCenter) or by running the host-list xe command. You can find the VM UUID on the General tab for the VM or by running the vm-list xe command. For more information, see Command line interface.

  2. In the xsconsole of the Citrix Hypervisor severing the crashed VM or in XenCenter, migrate all VMs to another host, then run the xe-toolstack-restart command.

Issues changing Workload Balancing servers

If you connect a pool to a different Workload Balancing server without disconnecting from Workload Balancing, both old and new Workload Balancing servers monitor the pool.

To solve this problem, you can take one of the following actions:

  • Shut down and delete the old Workload Balancing virtual appliance.
  • Manually stop the Workload Balancing services. These services are analysis, data collector, and Web service.

Note:

Do not use the pool-deconfigure-wlb xe command to disconnect a pool from the Workload Balancing virtual appliance or use the pool-initialize-wlb xe command to specify a different appliance.