Servers

A Citrix Provisioning server is any server that has stream services installed. Provisioning servers are used to stream software from virtual disks, as needed, to target devices. In some implementations, these disks reside directly on the provisioning server, and in other environments, provisioning servers get the virtual disk from a shared storage device.

Provisioning servers also retrieve and provide configuration information to and from the Citrix Provisioning database. Configuration options are available to ensure high availability and load-balancing of target device connections.

To configure a provisioning server and software components for the first time, run the Configuration Wizard. The Configuration Wizard can be rerun on a provisioning server later to change network configuration settings.

After the server components are installed, they are managed using the Citrix Provisioning console.

Tip:

When configuring provisioning servers, ensure that proper firewall isolation is observed so that the deployment provides a robust security boundary around all servers. Extend this isolation to the SQL server and disk storage, so that network access outside the security boundary is restricted. This configuration prevents viewing of weakly authenticated or unencrypted data flows.

At a minimum, isolate only those server instances that communicate with one another on their unauthenticated intra server communication channels. To isolate server instances, configure hardware firewalls to ensure that packets cannot be routed from outside this boundary to servers within the boundary. Extend this firewall protection paradigm to the SQL server and disk storage components where configurations do not have appropriate SQL server and disk storage links. Extending the firewall prevents unauthorized users from targeting these additional components.

Provisioning servers in the console

A provisioning server is any server that has Stream Services installed. These servers are used to stream software from vDisks, as needed, to target devices. In some implementations, vDisks reside directly on the provisioning server. In larger implementations, servers get the virtual disk from a shared-storage device on the network.

The Citrix Provisioning console is used to perform provisioning server management tasks such as editing the configuration settings or the properties of existing provisioning servers.

Servers appear in the console main window as members of a site within a farm. To manage servers that belong to a specific site, you must have the appropriate administrative role. These roles include site administrator for this site, or the farm administrator.

Note:

In the console, the appearance of the provisioning server icon indicates that server’s status.

In the console, provisioning servers are managed by performing actions on them. To view a list of actions that can be performed on a selected server, choose from the following options:

  • Click the Action menu in the menu bar.
  • Right-click on a provisioning server in the console.
  • Enable the Action pane from the Views menu.

Note:

Actions appear disabled if they do not apply to the selected provisioning server. See Management Tasks for task details.

Showing Citrix Provisioning server connections

To view and manage all target device connections to the provisioning server:

  1. Highlight a provisioning server in the console. Select Show connected devices from the Action menu, right-click menu, or Action pane. The Connected Target Devices dialog appears.
  2. Select one or more target devices in the table to perform any of the following connection tasks:
Option Description
Shutdown Shuts down target devices that are highlighted in the dialog.
Reboot Reboots target devices that are highlighted in the dialog.
Message Opens the Edit Message dialog to allow you to type, and then send a message to target devices highlighted in the dialog.

Note: When selecting Shutdown or Reboot, a dialog opens providing the option to type a message that displays on the affected devices. The Shutdown or Reboot options can be delayed by entering a delay time setting.

If a message confirms that the target device was successfully shut down or rebooted, but the icon in the console window does not change, select the Refresh button.

Balancing the target device load on provisioning servers

To achieve optimum server and target device performance within a highly available network configuration, enable load balancing for each virtual disk.

  1. Right-click on the vDisk in the console, then select the Load Balancing menu option. The vDisk Load Balancing dialog box appears. For details, see Servers.
  2. After enabling load balancing for the virtual disk, set the following extra load balancing algorithm customizations:
    • Subnet Affinity – When assigning the server and NIC combination to use to provide this virtual disk to target devices, select from the following subnet settings:
      • None – ignore subnets. Uses the least busy server. None is the default setting.
      • Best Effort – use the least busy server/NIC combination from within the same subnet. If no server/NIC combination is available within the subnet, select the least busy server from outside the subnet. If more than one server is available within the selected subnet, perform load balancing between those servers.
      • Fixed – use the least busy server/NIC combination from within the same subnet. Perform load balancing between servers within that subnet. If no server/NIC combination exists in the same subnet, do not boot target devices assigned to this virtual disk.
    • Rebalance Enabled using Trigger Percent – Enable this option to rebalance the number of target devices on each server when the trigger percent is exceeded. When enabled, Citrix Provisioning checks the trigger percent on each server approximately every 10 minutes. For example: If the trigger percent on this virtual disk is set to 25%, rebalancing occurs within 10 minutes if this server has 25% more load in comparison to other servers that can provide this virtual disk.

Note:

The load balance algorithm considers the Server power setting of each server when determining load.

Load balancing fails if:

  • Less than five target devices are using a particular server.
  • The average number of target devices using all qualifying servers is less than five.
  • The number of target devices that are booting on a given server is more than 20% of the total number of devices connected to the server. This configuration prevents load shift thrashing during a boot storm.

Load balancing is also considered when a target device boots. Citrix Provisioning determines which qualified provisioning server, with the least amount of load, provides the virtual disk. Whenever more qualified servers are brought online, rebalancing occurs automatically.

To implement load balancing in a high availability network configuration

  • Assign a power rating to each provisioning server on the Server properties’ General tab.
  • For each virtual disk, select the load balancing method and define any additional load balancing algorithm settings on the vDisk Load Balancing dialog box. For details, see Servers.

Note:

Target devices that not using a virtual disk in high availability mode are not diverted to a different server. If a virtual disk is misconfigured to have high availability enabled, but they are not using a valid high availability configuration. Provisioning servers, stores and target devices that use that virtual disk can lock up.

To rebalance provisioning server connections manually

  1. In the Citrix Provisioning console, highlight the provisioning servers to rebalance, right-click then select the Rebalance devices menu option. The Rebalance Devices dialog appears.
  2. Click Rebalance. A rebalance results message displays under the Status column.
  3. Click Close to exit the dialog.

Checking for provisioning server virtual disk access updates

To check for updates to vDisks that the selected provisioning server accesses:

  1. Right-click the provisioning server in the Details pane, then select Check for updates.
  2. Select the Automatic… menu option.
  3. Click OK on the confirmation message that appears. The virtual disk is automatically updated or is scheduled for an update.

Disabling write cache to improve performance when using storage device drives

Disable write caching to improve the performance when writing from a provisioning server to storage device drives such as an IDE or SATA drive.

In Windows, to disable write caching on the server hard drive for the storage device on which your vDisks are stored:

  1. On the provisioning server, open the Control Panel. Select Administrative Tools>Computer Management.
  2. Double-click the Disk Management node in the tree.
  3. Right-click the storage device for which Windows write caching is disabled.
  4. Select Properties, then click the Hardware tab.
  5. Click the Properties button.
  6. Click the Policies tab.
  7. Clear the Enable write caching on the disk check box.
  8. Click OK, then click OK again.
  9. Close the Computer Management window, then the Administrative Tools window.
  10. Right-click the provisioning server node in the console, then click Restart service. Alternatively, you can also rerun the Configuration Wizard to restart the services, or manually restart the services through the Windows Control Panel>Administrative Tools>Services window. At the Services window, right-click on the Stream Service, then select Start from the shortcut menu.

Providing provisioning servers with access to stores

For each store, select the provisioning servers that can access that store:

  1. In the Citrix Provisioning console, right-click on the Store, then select the Properties menu option. The Store Properties dialog appears.
  2. On the Servers tab, select the site where provisioning servers access this store.
  3. Enable the check box next to each provisioning server that can provide vDisks in this store, then click OK.