Maintain the printing environment 编辑

Maintaining the printing environment includes:

• Managing printer drivers
• Optimizing printing performance
• Displaying printer and managing print queues

Manage printer drivers

To minimize administrative overhead and the potential for print driver issues, Citrix recommends use of the Citrix Universal print driver.

If auto-creation fails, by default, the system installs a Windows-native printer driver provided with Windows. If a driver is not available, the system falls back to the Universal print driver. For more information about printer driver defaults, refer to Best practices, security considerations, and default operations.

If the Citrix Universal print driver is not an option for all scenarios, map printer drivers to minimize the amount of drivers installed on Multi-session OS machines. In addition, mapping printer drivers enables you to:

• Allow specified printers to use only the Citrix Universal print driver
• Allow or prevent printers to be created with a specified driver
• Substitute good printer drivers for outdated or corrupted drivers
• Substitute a driver that is available on Windows server for a client driver name

Prevent the automatic installation of printer drivers - The automatic installation of print drivers should be disabled to ensure consistency across Multi-session OS machines. This can be achieved through Citrix policies, Microsoft policies, or both. To prevent the automatic installation of Windows-native printer drivers, disable the Citrix policy setting Automatic installation of in-box printer drivers.

Map client printer drivers - Each client provides information about client-side printers during logon, including the printer driver name. During client printer autocreation, Windows server printer driver names are selected that correspond to the printer model names provided by the client. The autocreation process then uses the identified, available printer drivers to construct redirected client print queues.

Here is the general process for defining driver substitution rules and editing print settings for mapped client printer drivers:

1. To specify driver substitution rules for auto-created client printers, configure the Citrix policy setting Printer driver mapping and compatibility by adding the client printer driver name and selecting the server driver that you want to substitute for the client printer driver from the Find printer driver menu. You can use wildcards in this setting. For example, to force all HP printers to use a specific driver, specify HP* in the policy setting.
2. To ban a printer driver, select the driver name and choose the Do not create setting.
3. As needed, edit an existing mapping, remove a mapping, or change the order of driver entries in the list.
4. To edit the printing settings for mapped client printer drivers, select the printer driver, click Settings, and specify settings such as print quality, orientation, and color. If you specify a printing option that the printer driver does not support, that option has no effect. This setting overrides retained printer settings the user set during a previous session.
5. Citrix recommends testing the behavior of the printers in detail after mapping drivers, since some printer functionality can be available only with a specific driver.

When users log on the system checks the client printer driver compatibility list before it sets up the client printers.

Optimize printing performance

To optimize printing performance, use the Universal Print Server and Universal print driver. The following policies control printing optimization and compression:

• Universal printing optimization defaults. Specifies default settings for the Universal Printer when it is created for a session:
  • Desired image quality specifies the default image compression limit applied to universal printing. By default, Standard Quality is enabled, meaning that users can only print images using standard or reduced quality compression.
  • Enable heavyweight compression enables or disables reducing bandwidth beyond the compression level set by Desired image quality, without losing image quality. By default, heavyweight compression is disabled.
  • Image and Font Caching settings specify whether or not to cache images and fonts that appear multiple times in the print stream, ensuring each unique image or font is sent to the printer only once. By default, embedded images and fonts are cached.
  • Allow non-administrators to modify these settings specifies whether or not users can change the default print optimization settings within a session. By default, users are not allowed to change the default print optimization settings.
• Universal printing image compression limit. Defines the maximum quality and the minimum compression level available for images printed with the Universal print driver. By default, the image compression limit is set to Best Quality (lossless compression).
• Universal printing print quality limit. Specifies the maximum dots per inch (dpi) available for generating printed output in the session. By default, no limit is specified.

By default, all print jobs destined for network printers route from the Multi-session OS machine, across the network, and directly to the print server. Consider routing print jobs over the ICA connection if the network has substantial latency or limited bandwidth. To do that, disable the Citrix policy setting Direct connections to print servers. Data sent over the ICA connection is compressed, so less bandwidth is consumed as the data travels across the WAN.

Improve session performance by limiting printing bandwidth - While printing files from Multi-session OS machines to user printers, other virtual channels (such as video) may experience decreased performance due to competition for bandwidth especially if users access servers through slower networks. To prevent such degradation, you can limit the bandwidth used by user printing. By limiting the data transmission rate for printing, you make more bandwidth available in the HDX data stream for transmission of video, keystrokes, and mouse data.

Important:

The printer bandwidth limit is always enforced, even when no other channels are in use.

Use the following Citrix policy bandwidth printer settings to configure printing bandwidth session limits. To set the limits for the site, perform this task using Studio. To set the limits for individual servers, perform this task using the Group Policy Management Console in Windows locally on each Multi-session OS machine.

• The Printer redirection bandwidth limit setting specifies the bandwidth available for printing in kilobits per second (kbps).

• The Printer redirection bandwidth limit percent setting limits the bandwidth available for printing to a percentage of the overall bandwidth available.

  Note: To specify bandwidth as a percentage using the Printer redirection bandwidth limit percent setting, enable the Overall session bandwidth limit as well.

  If you enter values for both settings, the most restrictive setting (the lower value) is applied.

To obtain real-time information about printing bandwidth, use Citrix Director.

Load balance Universal Print Servers

The Universal Print Server solution can scale by adding more print servers into the load balance solution. There is no single point of failure as each VDA has its own load balancer to distribute the printing load to all print servers.

Use the policy settings, Universal Print Servers for load balancing and Universal Print Servers out-of-service threshold, to distribute the printing load across all the print servers in the load balance solution.

If there is an unforeseen failure of a print server, the failover mechanism of the load balancer in each VDA automatically redistributes the printer connections allocated on the failed print servers to the other available print servers such that all existing and incoming sessions function normally without affecting the user experience and without requiring the immediate administrator intervention.

Administrators can monitor the activity of the load balanced print servers using a set of performance counters to track the following on the VDA:

• List of load balanced print servers on the VDA and their state (available, unavailable)
• Number of printer connections accepted by each print server
• Number of printer connections failed on each print server
• Number of active printer connection on each print server
• Number of pending printer connections on each print server

Display and manage print queues

The following table summarizes where you can display printers and manage print queues in your environment.

Note:

Print queues for network printers that use the network printing pathway are private and cannot be managed through the system.