Administer Workload Balancing

After Workload Balancing has been running for a while, there are routine tasks that you might need to perform to keep Workload Balancing running optimally. You might need to perform these tasks because of changes to your environment (such as different IP addresses or credentials), hardware upgrades, or routine maintenance.

Connect to the Workload Balancing virtual appliance

After Workload Balancing configuration, connect the pool you want managed to the Workload Balancing virtual appliance using either the CLI or XenCenter. Likewise, you might need to reconnect to the same virtual appliance at some point.

To connect a pool to your Workload Balancing virtual appliance, you need the following information:

  • IP address or FQDN of the Workload Balancing virtual appliance

    • To obtain the IP address for the Workload Balancing virtual appliance:

      1. In XenCenter, go to the Workload Balancing virtual appliance Console tab.
      2. Log in as root with the root password you created when you imported the appliance.
      3. Run the following command: ifconfig.
    • To specify the Workload Balancing FQDN when connecting to the Workload Balancing server, first add its host name and IP address to your DNS server.

  • The port number of the Workload Balancing virtual appliance. By default, Citrix Hypervisor connects to Workload Balancing on port 8012.

    Only edit the port number when you have changed it during Workload Balancing Configuration. The port number specified during Workload Balancing Configuration, in any firewall rules, and in the Connect to WLB Server dialog must match.

  • Credentials for the resource pool you want Workload Balancing to monitor.

  • Credentials for the Workload Balancing account you created during Workload Balancing configuration.

    This account is often known as the Workload Balancing user account. Citrix Hypervisor uses this account to communicate with Workload Balancing. You created this account on the Workload Balancing virtual appliance during Workload Balancing Configuration

(1) Citrix Hypervisor communicates with Workload Balancing using an account you created during Workload Balancing Configuration. (2) the Workload Balancing virtual appliance authenticates to Citrix Hypervisor using the credentials for the pool.

When you first connect to Workload Balancing, it uses the default thresholds and settings for balancing workloads. Automatic features, such as automated optimization mode, power management, and automation, are disabled by default.

Working with certificates

If you want to upload a different (trusted) certificate or configure certificate verification, note the following before connecting your pool to Workload Balancing:

  • If you want Citrix Hypervisor to verify the self-signed Workload Balancing certificate, you must use the Workload Balancing IP address to connect to Workload Balancing. The self-signed certificate is issued to Workload Balancing based on its IP address.

  • If you want to use a certificate from a certificate authority, it is easier to specify the FQDN when connecting to Workload Balancing. However, you can specify a static IP address in the Connect to WLB Server dialog. Use this IP address as the Subject Alternative Name (SAN) in the certificate.

For more information, see Certificates.

To connect your pool to the Workload Balancing virtual appliance

  1. In XenCenter, select your resource pool and in its Properties pane, click the WLB tab. The WLB tab displays the Connect button.

    XenCenter GUI with the WLB panel open.

  2. In the WLB tab, click Connect. The Connect to WLB Server dialog box appears.

    The Connect to WLB Server wizard.

  3. In the Server Address section, enter the following:

    1. In the Address box, type the IP address or FQDN of the Workload Balancing virtual appliance. For example, WLB-appliance-computername.yourdomain.net.

    2. (Optional) If you changed the Workload Balancing port during Workload Balancing Configuration, enter the port number in the Port box. Citrix Hypervisor uses this port to communicate with Workload Balancing.

      By default, Citrix Hypervisor connects to Workload Balancing on port 8012.

  4. In the WLB Server Credentials section, enter the user name and password that the pool uses to connect to the Workload Balancing virtual appliance.

    The Update Credentials dialog. The fields are user name and Password.

    These credentials must be for the account you created during Workload Balancing configuration. By default, the user name for this account is wlbuser.

  5. In the Citrix Hypervisor Credentials section, enter the user name and password for the pool you are configuring. Workload Balancing uses these credentials to connect to the servers in that pool.

    The Citrix Hypervisor Credentials dialog. The fields are user name and Password.

    To use the credentials with which you are currently logged into Citrix Hypervisor, select Use the current XenCenter credentials. If you have assigned a role to this account using the role-based access control (RBAC) feature, ensure that the role has sufficient permissions to configure Workload Balancing. For more information, see Workload Balancing Access Control Permissions.

After connecting the pool to the Workload Balancing virtual appliance, Workload Balancing automatically begins monitoring the pool with the default optimization settings. If you want to modify these settings or change the priority given to resources, wait until the XenCenter Log shows that discovery is finished before proceeding.

Important:

After Workload Balancing is running for a time, if you do not receive optimal recommendations, evaluate your performance thresholds as described in Configure Workload Balancing behavior. It is critical to set Workload Balancing to the correct thresholds for your environment or its recommendations might not be appropriate.

Workload Balancing access control permissions

When Role Based Access Control (RBAC) is implemented in your environment, all user roles can display the WLB tab. However, not all roles can perform all operations. The following table lists the minimum role administrators require to use Workload Balancing features:

Permission Minimum Required Role
Configure, Initialize, Enable, Disable WLB Pool Operator
Apply WLB Optimization Recommendations in WLB tab Pool Operator
Modify WLB report subscriptions Pool Operator
Accept WLB Placement Recommendations VM Power Admin
Generate WLB Reports, including the Pool Audit Trail report Read Only
Display WLB Configuration Read Only

The following table provides more details about permissions.

Permission Allows Assignee To
Configure, Initialize, Enable, Disable WLB Configure WLB
  Initialize WLB and change WLB servers
  Enable WLB
  Disable WLB
Apply WLB Optimization Recommendations in WLB tab Apply any optimization recommendations that appear in the WLB tab
Modify WLB report subscriptions Change the WLB report generated or its recipient
Accept WLB Placement Recommendations Select one of the servers Workload Balancing recommends for placement
Generate WLB Reports, including the Pool Audit Trail report View and run WLB reports, including the Pool Audit Trail report
Display WLB Configuration View WLB settings for a pool as shown on the WLB tab

If a user tries to use Workload Balancing and that user doesn’t have sufficient permissions, a role elevation dialog appears. For more information about RBAC, see Role-based access control.

Reconfigure a pool to use another Workload Balancing virtual appliance

You can reconfigure a resource pool to use a different Workload Balancing virtual appliance.

If you are moving from an older version of the Workload Balancing virtual appliance to the latest version, before disconnecting your old virtual appliance, you can migrate its data to the new version of the virtual appliance. For more information, see Migrate data from an existing virtual appliance.

After disconnecting a pool from the old Workload Balancing virtual appliance, you can connect the pool by specifying the name of the new Workload Balancing virtual appliance.

To use a different Workload Balancing virtual appliance:

  1. (Optional) Migrate data from an older version of the virtual appliance. For more information, see Migrate data from an existing virtual appliance.

  2. In XenCenter, from the Pool menu, select Disconnect Workload Balancing Server and click Disconnect when prompted.

  3. In the WLB tab, click Connect. The Connect to WLB Server dialog appears.

  4. Connect to the new virtual appliance. For more information, see Connect to the Workload Balancing virtual appliance

Change the Workload Balancing credentials

After initial configuration, if you want to update the credentials Citrix Hypervisor and the Workload Balancing appliance use to communicate, use the following process:

  1. To pause Workload Balancing, go to the WLB tab and click Pause.

  2. Change the Workload Balancing credentials by running the wlbconfig command. For more information, see Workload Balancing Commands.

  3. Re-enable Workload Balancing and specify the new credentials.

  4. After the progress bar completes, click Connect.

    The Connect to WLB Server dialog box appears.

  5. Click Update Credentials.

  6. In the Server Address section, modify the following settings as appropriate:

    • In the Address box, type the IP address or FQDN of the Workload Balancing appliance.

    • (Optional.) If you changed the port number during Workload Balancing Configuration, enter that port number. The port number you specify in this box and during Workload Balancing Configuration is the port number Citrix Hypervisor uses to connect to Workload Balancing.

      By default, Citrix Hypervisor connects to Workload Balancing on port 8012.

      Note:

      Only edit this port number if you changed it when you ran the Workload Balancing Configuration wizard. The port number value specified when you ran the Workload Balancing Configuration wizard and the Connect to WLB Server dialog must match.

  7. In the WLB Server Credentials section, enter the user name (for example, wlbuser) and password the computers running Citrix Hypervisor uses to connect to the Workload Balancing server.

  8. In the Citrix Hypervisor Credentials section, enter the user name and password for the pool you are configuring (typically the password for the pool master). Workload Balancing uses these credentials to connect to the computers running Citrix Hypervisor in that pool.

  9. In the Citrix Hypervisor Credentials section, enter the user name and password for the pool you are configuring. Workload Balancing uses these credentials to connect to the computers running Citrix Hypervisor in that pool.

    To use the credentials with which you are currently logged into Citrix Hypervisor, select Use the current XenCenter credentials.

Change the Workload Balancing IP address

To change the Workload Balancing IP address, do the following:

  1. Stop the Workload Balancing services by running the service workloadbalancing stop command on the virtual appliance.

  2. Change the Workload Balancing IP address by running the ifconfig command on the virtual appliance.

  3. Re-enable Workload Balancing and specify the new IP address.

  4. Start the Workload Balancing services by running the service workloadbalancing start command on the virtual appliance.

Change the Workload Balancing virtual appliance configuration

When you first install the Workload Balancing virtual appliance it has the following default configuration:

Configuration Value
Number of vCPUs 2
Memory (RAM) 2 GB
Disk space 30 GB

These values are suitable for most environments. If you are monitoring very large pools, you might consider increasing these values.

Change the number of vCPUs assigned to the virtual appliance

By default, the Workload Balancing virtual appliance is assigned 2 vCPUs. This value is sufficient for pools hosting 1000 VMs. You do not usually need to increase it. Only decrease the number of vCPUs assigned to the virtual appliance if you have a small environment.

This procedure explains how to change the number of vCPUs assigned to the Workload Balancing virtual appliance. Shut down the virtual appliance before performing these steps. Workload Balancing is unavailable for approximately five minutes.

  1. Shut down the Workload Balancing virtual appliance.

  2. In the XenCenter resource pane, select the Workload Balancing virtual appliance.

  3. In the virtual appliance General tab, click Properties. The Properties dialog opens.

  4. In the CPU tab of the Properties dialog, edit the CPU settings to the required values.

  5. Click OK.

  6. Start the Workload Balancing virtual appliance.

The new vCPU settings take affect when the virtual appliance starts.

Resize the virtual appliance memory

By default, the Workload Balancing virtual appliance is assigned 2 GB of memory.

For large pools, set the Workload Balancing virtual appliance to consume the maximum amount of memory you can make available to it (even up to 16 GB). Do not be concerned about high memory utilization. High memory utilization is normal for the virtual appliance because the database always consumes as much memory as it can obtain.

Note:

Dynamic Memory Control is not supported with the Workload Balancing virtual appliance. Set a fixed value for the maximum memory to assign to the virtual appliance.

This procedure explains how to resize the memory of the Workload Balancing virtual appliance. Shut down the virtual appliance before performing these steps. Workload Balancing is unavailable for approximately five minutes.

  1. Shut down the Workload Balancing virtual appliance.

  2. In the XenCenter resource pane, select the Workload Balancing virtual appliance.

  3. In the virtual appliance Memory tab, click Edit. The Memory Settings dialog opens.

  4. Edit the memory settings to the required values.

  5. Click OK.

  6. Start the Workload Balancing virtual appliance.

The new memory settings take affect when the virtual appliance starts.

Resize the virtual appliance disk

By default, the Workload Balancing virtual appliance is assigned 30 GB of disk space.

The greater the number of VMs the Workload Balancing virtual appliance is monitoring, the more disk space it consumes per day.

You can estimate the amount of disk size that the virtual appliance needs by using the following formula:

Total estimated disk size = ( ( number of days * average disk usage ) + base disk usage ) * grooming multiplier
  • number of days is the number of days of data to retain

  • average disk usage depends on the number of VMs being monitored. The following values give an approximation for certain numbers of VMs:

    • For 200 VMs - 0.246 GB/day
    • For 400 VMs - 0.505 GB/day
    • For 600 VMs - 0.724 GB/day
    • For 800 VMs - 0.887 GB/day
  • base disk usage is 2.4 GB
  • grooming multiplier is 1.25. This multiplier accounts for the amount of disk space required by grooming. It assumes that grooming requires an additional 25% of the total calculated disk space.

This procedure explains how to resize the virtual disk of the Workload Balancing virtual appliance. Shut down the virtual appliance before performing these steps. Workload Balancing is unavailable for approximately five minutes.

Warning:

We recommend taking a snapshot of your data before performing this procedure. Incorrectly performing these steps can result in corrupting the Workload Balancing virtual appliance.

  1. Shut down the Workload Balancing virtual appliance.

  2. In the XenCenter resource pane, select the Workload Balancing virtual appliance.

  3. Click the Storage tab.

  4. Select the vdi_xvda disk, and click the Properties button.

  5. In the vdi_xvda Properties dialog, select Size and Location.

  6. Increase the disk size as needed, and click OK.

  7. Start the Workload Balancing virtual appliance and log in to it.

  8. Run the following command on the Workload Balancing virtual appliance:

     resize2fs /dev/xvda
    
  9. Run the df –h command to confirm the new disk size.

Installing resize2fs

If the resize2fs tool is not installed on the Workload Balancing virtual appliance, you can install it by using the following steps.

If you are connected to the internet, run the following command on the Workload Balancing virtual appliance:

yum install -y --enablerepo=base,updates --disablerepo=citrix-* e2fsprogs

If there is no internet access:

  1. Download the following from https://centos.pkgs.org/7/centos-x86_64/.

    • libss-1.42.9-7.el7.i686.rpm
    • e2fsprogs-libs-1.42.9-7.el7.x86_64.rpm
    • e2fsprogs-1.42.9-7.el7.x86_64.rpm
  2. Upload them to Workload Balancing VM using SCP or any other suitable tool.

  3. Run the following command from Workload Balancing virtual appliance:

    rpm -ivh libss-*.rpm e2fsprogs-*.rpm
    

    The tool resize2fs is now installed.

Stop Workload Balancing

Because Workload Balancing is configured at the pool level, when you want it to stop managing a pool, you must do one of the following:

Pause Workload Balancing. Pausing Workload Balancing stops XenCenter from displaying recommendations for the specified resource pool and managing the pool. Pausing is designed for a short period and lets you resume monitoring without having to reconfigure. When you pause Workload Balancing, data collection stops for that resource pool until you enable Workload Balancing again.

  1. In XenCenter, select the resource pool for which you want to disable Workload Balancing.

  2. In the WLB tab, click Pause. A message appears on the WLB tab indicating that Workload Balancing is paused.

Tip:

To resume monitoring, click the Resume button in the WLB tab.

Disconnect the pool from Workload Balancing. Disconnecting from the Workload Balancing virtual appliance breaks the connection between the pool and if possible, deletes the pool data from the Workload Balancing database. When you disconnect from Workload Balancing, Workload Balancing stops collecting data on the pool.

  1. In XenCenter, select the resource pool on which you want to stop Workload Balancing.

  2. From the Infrastructure menu, select Disconnect Workload Balancing Server. The Disconnect Workload Balancing server dialog box appears.

  3. Click Disconnect to stop Workload Balancing from monitoring the pool permanently.

Tip:

If you disconnected the pool from the Workload Balancing virtual appliance, to re-enable Workload Balancing on that pool, you must reconnect to a Workload Balancing appliance. For information, see the Connect to the Workload Balancing Virtual Appliance.

Enter maintenance mode with Workload Balancing enabled

With Workload Balancing enabled, if you put a server in maintenance mode, Citrix Hypervisor migrates the VMs running on that server to their optimal servers when available. Citrix Hypervisor uses Workload Balancing recommendations that are based on performance data, your placement strategy, and performance thresholds to select the optimal server.

If an optimal server is not available, the words Click here to suspend the VM appear in the Enter Maintenance Mode wizard. In this case, because there is not a server with sufficient resources to run the VM, Workload Balancing does not recommend a placement. You can either suspend this VM or exit maintenance mode and suspend a VM on another server in the same pool. Then, if you reenter the Enter Maintenance Mode dialog box, Workload Balancing might be able to list a server that is a suitable candidate for migration.

Note:

When you take a server off-line for maintenance and Workload Balancing is enabled, the words “Workload Balancing” appear in the Enter Maintenance Mode wizard.

To enter maintenance mode with Workload Balancing enabled:

  1. In the Resources pane of XenCenter, select the physical server that you want to take off-line.

  2. From the Server menu, select Enter Maintenance Mode.

  3. In the Enter Maintenance Mode wizard, click Enter maintenance mode.

    The VMs running on the server are automatically migrated to the optimal server based on the Workload Balancing performance data, your placement strategy, and performance thresholds.

To take the server out of maintenance mode:

  1. Right-click the server and select Exit Maintenance Mode.

    When you remove a server from maintenance mode, Citrix Hypervisor automatically restores that server’s original VMs to that server.

Remove the Workload Balancing virtual appliance

To remove the Workload Balancing virtual appliance, we recommend you use the standard procedure to delete VMs from XenCenter.

When you delete the Workload Balancing virtual appliance, the PostgreSQL database containing the Workload Balancing is deleted. To save this data, you must migrate it from the database before deleting the Workload Balancing virtual appliance.

Manage the Workload Balancing database

The Workload Balancing database is a PostgreSQL database. PostgreSQL is an open-source relational database. You can find documentation for PostgreSQL by searching the web.

The following information is intended for database administrators and advanced users of PostgreSQL who are comfortable with database administration tasks. If you are not experienced with PostgreSQL, we recommend that you become familiar with it before you attempt the database tasks in the sections that follow.

By default, the PostgreSQL user name is postgres. You set the password for this account during Workload Balancing configuration.

The amount of historical data you can store is based on the size of the virtual disk allocated to Workload Balancing and the minimum required space. By default, the size of the virtual disk allocated to Workload Balancing is 30 GB. In terms of managing the database, you can control the space that database data consumes by configuring database grooming. For more information, see Database grooming parameters.

To store a lot of historical data, for example if you want to enable the Pool Audit trail Report, you can do either of the following:

  • Make the virtual disk size assigned to the Workload Balancing virtual appliance larger. To do so, import the virtual appliance, and increase the size of the virtual disk by following the steps in Resize the virtual appliance disk.

  • Create periodic duplicate backup copies of the data by enabling remote client access to the database and using a third-party database administration tool.

Access the database

The Workload Balancing virtual appliance has firewall configured in it. Before you can access the database, you must add the postgresQL server port to the iptables.

  1. From the Workload Balancing virtual appliance console, run the following command:

    iptables -A INPUT -i eth0 -p tcp -m tcp --dport 5432 -m \
    state --state NEW,ESTABLISHED -j ACCEPT
    
  2. (Optional) To make this configuration persist after the virtual appliance is rebooted, run the following command:

    iptables-save > /etc/sysconfig/potables
    

Control database grooming

The Workload Balancing database automatically deletes the oldest data whenever the virtual appliance reaches the minimum amount of disk space that Workload Balancing requires to run. By default, the minimum amount of required disk space is set to 1,024 MB.

The Workload Balancing database grooming options are controlled through the file wlb.conf.

When there is not enough disk space left on the Workload Balancing virtual appliance, Workload Balancing automatically starts grooming historical data. The process is as follows:

  1. At a predefined grooming interval, the Workload Balancing data collector checks if grooming is required. Grooming is required if the database data has grown to the point where the only space that remains unused is the minimum required disk space. Use GroomingRequiredMinimumDiskSizeInMB to set the minimum required disk space.

    You can change the grooming interval if desired using GroomingIntervalInHour. However, by default Workload Balancing checks to see if grooming is required once per hour.

  2. If grooming is required, Workload Balancing begins by grooming the data from the oldest day. Workload Balancing then checks to see if there is now enough disk space for it to meet the minimum disk-space requirement.

  3. If the first grooming did not free enough disk space, then Workload Balancing repeats grooming up to GroomingRetryCounter times without waiting for GroomingIntervalInHour hour.

  4. If the first or repeated grooming freed enough disk space, then Workload Balancing waits for GroomingIntervalInHour hour and returns to Step 1.

  5. If the grooming initiated by the GroomingRetryCounter did not free enough disk space, then Workload Balancing waits for GroomingIntervalInHour hour and returns to Step 1.

Database grooming parameters

There are five parameters in the wlb.conf file that control various aspects of database grooming. They are as follows:

  • GroomingIntervalInHour. Controls how many hours elapse before the next grooming check is done. For example, if you enter 1, Workload Balancing checks the disk space hourly. If you enter 2, Workload Balancing checks disk space every two hours to determine if grooming must occur.

  • GroomingRetryCounter. Controls the number of times Workload balancing tries rerunning the grooming database query.

  • GroomingDBDataTrimDays. Controls the number of days worth of data Workload Balancing deletes from the database each time it tries to groom data. The default value is one day.

  • GroomingDBTimeoutInMinute. Controls the number of minutes that the database grooming takes before it times out and is canceled. If the grooming query takes longer than is expected and does not finish running within the timeout period, the grooming task is canceled. The default value is 0 minutes, which means that database grooming never times out.

  • GroomingRequiredMinimumDiskSizeInMB. Controls the minimum amount of free space left in the virtual disk assigned to the Workload Balancing virtual appliance. When the data in the virtual disk grows until there is only minimum disk size left on the virtual disk, Workload Balancing triggers database grooming. The default value is 2,048 MB.

To edit these values, see Edit the Workload Balancing configuration file.

Change the database password

We recommend using the wlbconfig command to change the database password. For more information, see Modify the Workload Balancing configuration options. Do not change the password by modifying the wlb.conf file.

Archive database data

To avoid having older historical data deleted, you can, optionally, copy data from the database for archiving. To do so, you must perform the following tasks:

  1. Enable client authentication on the database.

  2. Set up archiving using the PostgreSQL database administration tool of your choice.

Enable client authentication to the database

While you can connect directly to the database through the Workload Balancing console, you can also use a PostgreSQL database management tool. After downloading a database management tool, install it on the system from which you want to connect to the database. For example, you can install the tool on the same laptop where you run XenCenter.

Before you can enable remote client authentication to the database, you must:

  1. Modify the database configuration files, including pg_hba.conf file and the postgresql.conf, to allow connections.

  2. Stop the Workload Balancing services, restart the database, and then restart the Workload Balancing services.

  3. In the database management tool, configure the IP address of the database (that is, the IP address of the Workload Balancing VPX) and the database password.

Modify the database configuration files

To enable client authentication on the database, you must modify the following files on the Workload Balancing virtual appliance: the pg_hba.conf file and the postgresql.conf file.

To edit the pg_hba.conf file:

  1. Modify the pg_hba.conf file. From the Workload Balancing virtual appliance console, open the pg_hba.conf file with an editor, such as VI. For example:

    vi /var/lib/pgsql/9.0/data/pg_hba.conf
    
  2. If your network uses IPv4, add the IP address from the connecting computer to this file. For example:

    In the configuration section, enter the following under #IPv4 local connections:

    • TYPE: host
    • DATABASE: all
    • USER: all
    • CIDR-ADDRESS: 0.0.0.0/0
    • METHOD: trust
  3. Enter your IP address in the CIDR-ADDRESS field.

    Note:

    Instead of entering 0.0.0.0/0, you can enter your IP address and replace the last three digits with 0/24. The trailing “24” after the / defines the subnet mask and only allows connections from IP addresses within that subnet mask.

    When you enter trust for the Method field, it enables the connection to authenticate without requiring a password. If you enter password for the Method field, you must supply a password when connecting to the database.

  4. If your network uses IPv6, add the IP address from the connecting computer to this file. For example:

    Enter the following under #IPv6 local connections:

    • TYPE: host
    • DATABASE: all
    • USER: all
    • CIDR-ADDRESS: ::0/0
    • METHOD: trust

    Enter the IPv6 addresses in the CIDR-ADDRESS field. In this example, the ::0/0 opens the database up to connections from any IPv6 addresses.

  5. Save the file and quit the editor.

  6. After changing any database configurations, you must restart the database to apply the changes. Run the following command:

    service postgresql-9.0 restart
    

To edit the postgresql.conf file:

  1. Modify the postgresql.conf file. From the Workload Balancing virtual appliance console, open the postgresql.conf file with an editor, such as VI. For example:

    vi /var/lib/pgsql/9.0/data/postgresql.conf
    
  2. Edit the file so that it listens on any port and not just the local host. For example:

    1. Find the following line:

      # listen_addresses='localhost'
      
    2. Remove the comment symbol (#) and edit the line to read as follows:

      listen_addresses='*'
      
  3. Save the file and quit the editor.

  4. After changing any database configurations, you must restart the database to apply the changes. Run the following command:

    service postgresql-9.0 restart
    

Change the database maintenance window

Workload Balancing automatically performs routine database maintenance daily at 12:05AM GMT (00:05), by default. During this maintenance window, data collection occurs but the recording of data might be delayed. However, the Workload Balancing user interface controls are available during this period and Workload Balancing still makes optimization recommendations.

Note:

To avoid a loss of Workload Balancing:

  • During the maintenance window, the Workload Balancing server restarts. Ensure that you do not restart your VMs at the same time.
  • At other times, when restarting all VMs in your pool, do not restart the Workload Balancing server.

Database maintenance includes releasing allocated unused disk space and reindexing the database. Maintenance lasts for approximately 6 to 8 minutes. In larger pools, maintenance might last longer, depending on how long Workload Balancing takes to perform discovery.

Depending on your time zone, you might want to change the time when maintenance occurs. For example, in the Japan Standard Time (JST) time zone, Workload Balancing maintenance occurs at 9:05 AM (09:05), which can conflict with peak usage in some organizations. If you want to specify a seasonal time change, such as Daylight Saving Time or summer time, you must build the change into value you enter.

To change the maintenance time:

  1. In the Workload Balancing console, run the following command from any directory:

    crontab -e
    

    Workload Balancing displays the following:

    05 0 * * * /opt/vpx/wlb/wlbmaintenance.sh
    

    The value 05 0 represents the default time for Workload Balancing to perform maintenance in minutes (05) and then hours (0). (The asterisks represent the day, month, and year the job runs: Do not edit these fields.) The entry 05 0 indicates that database maintenance occurs at 12:05 AM, or 00:05, Greenwich Mean Time (GMT) every night. This setting means that if you live in New York, the maintenance runs at 7:05 PM (19:05) during winter months and 8:05 PM in summer months.

    Important:

    Do not edit the day, month, and year the job runs (as represented by asterisks). Database maintenance must run daily.

  2. Enter the time at which you want maintenance to occur in GMT.

  3. Save the file and quit the editor.

Customize Workload Balancing

Workload Balancing provides several methods of customization:

  • Command lines for scripting. For more information, see Workload Balancing commands.

  • Host Power On scripting support. You can also customize Workload Balancing (indirectly) through the Host Power On scripting. For more information, see Hosts and resource pools.

Upgrade Workload Balancing

Online upgrading of Workload Balancing has been deprecated for security reasons. Customers cannot upgrade by using the yum repo anymore. Customers can upgrade Workload Balancing to the latest version by importing the latest Workload Balancing virtual appliance downloadable at https://www.citrix.com/downloads/citrix-hypervisor/product-software/.

Workload Balancing commands

This section provides a reference for the Workload Balancing commands. You can perform these commands from the Citrix Hypervisor server or console to control Workload Balancing or configure Workload Balancing settings on the Citrix Hypervisor server. This appendix includes xe commands and service commands.

Run the following service commands on the Workload Balancing appliance. To do so, you must log in to the Workload Balancing virtual appliance.

Log in to the Workload Balancing virtual appliance

Before you can run any service commands or edit the wlb.conf file, you must log in to the Workload Balancing virtual appliance. To do so, you must enter a user name and password. Unless you created extra user accounts on the virtual appliance, log in using the root user account. You specified this account when you ran Workload Balancing Configuration wizard (before you connected your pool to Workload Balancing). You can, optionally, use the Console tab in XenCenter to log in to the appliance.

To log in to the Workload Balancing virtual appliance:

  1. At the login prompt, enter the account user name.

  2. At the Password prompt, enter the password for the account:

    Note:

    To log off from the Workload Balancing virtual appliance, simply type logout at the command prompt.

wlb restart

Run the wlb restart command from anywhere in the Workload Balancing appliance to stop and then restart the Workload Balancing Data Collection, Web Service, and Data Analysis services.

wlb start

Run the wlb start command from anywhere in the Workload Balancing appliance to start the Workload Balancing Data Collection, Web Service, and Data Analysis services.

wlb stop

Run the wlb stop command from anywhere in the Workload Balancing appliance to stop the Workload Balancing Data Collection, Web Service, and Data Analysis services.

wlb status

Run the wlb status command from anywhere in the Workload Balancing appliance to determine the status of the Workload Balancing server. After you run this command, the status of the three Workload Balancing services (the Web Service, Data Collection Service, and Data Analysis Service) is displayed.

Modify the Workload Balancing configuration options

Many Workload Balancing configurations, such as the database and web-service configuration options, are stored in the wlb.conf file. The wlb.conf file is a configuration file on the Workload Balancing virtual appliance.

To modify the most commonly used options, use the command wlb config. Running the wlb config command on the Workload Balancing virtual appliance lets you rename the Workload Balancing user account, change its password, or change the PostgreSQL password. After you run this command, the Workload Balancing services are restarted.

Run the following command on the Workload Balancing virtual appliance:

wlb config

The screen displays a series of questions guiding you through changing your Workload Balancing user name and password and the PostgreSQL password. Follow the questions on the screen to change these items.

Important:

Double-check any values you enter in the wlb.conf file: Workload Balancing does not validate values in the wlb.conf file. Therefore, if the configuration parameters you specify are not within the required range, Workload Balancing does not generate an error log.

Edit the Workload Balancing configuration file

You can modify Workload Balancing configuration options by editing the wlb.conf file, which is stored in /opt/vpx/wlb directory on the Workload Balancing virtual appliance. In general, only change the settings in this file with guidance from Citrix. However, there are three categories of settings you can change if desired:

  • Workload Balancing account name and password. It is easier to modify these credentials by running the wlb config command.
  • Database password. This value can be modified using the wlb.conf file. However, Citrix recommends modifying it through the wlb config command since this command modifies the wlb.conf file and automatically updates the password in the database. If you choose to modify the wlb.conf file instead, you must run a query to update the database with the new password.
  • Database grooming parameters. You can modify database grooming parameters, such as the database grooming interval, using this file by following the instructions in the database management section. However, if you do so, Citrix recommends using caution.

For all other settings in the wlb.conf file, Citrix currently recommends leaving them at their default, unless Citrix instructed you to modify them.

To edit the wlb.conf file:

  1. Run the following from the command prompt on the Workload Balancing virtual appliance (using VI as an example):

    vi /opt/vpx/wlb/wlb.conf
    

    The screen displays several different sections of configuration options.

  2. Modify the configuration options, and exit the editor.

You do not need to restart Workload Balancing services after editing the wlb.conf file. The changes go into effect immediately after exiting the editor.

Important:

Double-check any values you enter in the wlb.conf file: Workload Balancing does not validate values in the wlb.conf file. Therefore, if the configuration parameters you specify are not within the required range, Workload Balancing does not generate an error log.

Increase the detail in the Workload Balancing log

The Workload Balancing log provides a list of events on the Workload Balancing virtual appliance, including actions for the analysis engine, database, and audit log. This log file is found in this location: /var/log/wlb/LogFile.log.

You can, if desired, increase the level of detail the Workload Balancing log provides. To do so, modify the Trace flags section of the Workload Balancing configuration file (wlb.conf), which is found in the following location: /opt/vpx/wlb/wlb.conf. Enter a 1 or true to enable logging for a specific trace and a 0 or false to disable logging. For example, to enable logging for the Analysis Engine trace, enter:

AnalEngTrace=1

You might want to increase logging detail before reporting an issue to Citrix Technical Support or when troubleshooting.

Logging Option Trace Flag Benefit or Purpose
Analysis Engine Trace AnalEngTrace Logs details of the analysis engine calculations. Shows details of the decisions the analysis engine is making and potentially gain insight into the reasons Workload Balancing is not making recommendations.
Database Trace DatabaseTrace Logs details about database reads/writes. However, leaving this trace on increases the log file size quickly.
Data Collection Trace DataCollectionTrace Logs the actions of retrieving metrics. This value lets you see the metrics Workload Balancing is retrieving and inserting into the Workload Balancing data store. However, leaving this trace on increases the log file size quickly.
Data Compaction Trace DataCompactionTrace Logs details about how many milliseconds it took to compact the metric data.
Data Event Trace DataEventTrace This trace provides details about events Workload Balancing catches from Citrix Hypervisor.
Data Grooming Trace DataGroomingTrace This trace provides details about the database grooming.
Data Metrics Trace DataMetricsTrace Logs details about the parsing of metric data. Leaving this trace on increases the log-file size quickly.
Queue Management Trace QueueManagementTrace Logs details about data collection queue management processing. (This option is for internal use.)
Data Save Trace DataSaveTrace Logs details about the pool being saved to the database.
Score server Trace ScoreHostTrace Logs details about how Workload Balancing is arriving at a score for a host. This trace shows the detailed scores generated by Workload Balancing when it calculates the star ratings for selecting optimal servers for VM placement.
Audit Log Trace AuditLogTrace Shows the action of the audit log data being captured and written. (This option is only for internal use and does not provide information that is captured in the audit log.) However, leaving this trace on increases the log file size quickly.
Scheduled Task Trace ScheduledTaskTrace Logs details about scheduled tasks. For example, if your scheduled mode changes are not working, you might want to enable this trace to investigate the cause.
Web Service Trace WlbWebServiceTrace Logs details about the communication with the web-service interface.