After upgrade to 7.11 VDA, Black/Blank screen appears on the monitors while connecting to ICA session.
book
Article ID: CTX218217
calendar_today
Updated On:
Description
After upgrading a Windows 7 machine to 7.11 VDA the user is no longer able to span across multiple monitors. Reverting back to VDA version 7.9 resolves this issue.
Environment
Caution! Using Registry Editor incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.
Resolution
Complete the following procedure:
- Check for the current "System Video Memory" allocation located in the Control Panel, Display, Advanced Settings:
2. Calculate the video memory that is required for monitors using the following formula:Note: This formula is specific to VDA version 7.11. SumOfAllMons (Width * Height) * 4 / 0.3, where width and height are resolution of the monitor.For VDA 7.9 and earlier, refer http://support.citrix.com/article/CTX200257Example: Consider the resolution of monitor 1 is 1920*1200 and monitor 2 is 1366*768.Then SumOfAllMons will be (1920*1200 + 1366*768).Note:
There is no hard and fast rule that will work for all cases as composited desktops have random overhead in video memory so we have to allocate additional memory for this overhead. To get a visualization of the video memory required and size up the MaxVideoMemoryBytes for your specific environment, download sysinternals process explorer and observe the GPU Dedicated Memory graph (View > System Information, or Ctrl+I >GPU tab) inside an active Citrix connection:

3.
Open the registry (regedit) and navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\vbdenum 4. Increase the value of "MaxVideoMemoryBytes” REG_DWORD value to the above calculated memory.
5. Reboot the VDA. Note: The MaxVideoMemoryBytes key(s) should only be used in conjunction with the "Citrix Systems - WDDM Display Driver". If the "Citrix Display Only Adapter" is in use then these keys should not be set as memory is allocated dynamically.
Problem Cause
In the VDA, the Citrix WDDM driver allocates 64 MB by default for the video memory buffer at boot time, but for multi monitor scenario it is not sufficient.
Issue/Introduction
Black or Blank Screen when connecting to an ICA session
Was this article helpful?
thumb_up
Yes
thumb_down
No