What is the pcAnywhere "Mirror Driver"?

Article:TECH110005  |  Created: 2008-01-08  |  Updated: 2013-07-05  |  Article URL http://www.symantec.com/docs/TECH110005
Article Type
Technical Solution

Product(s)

Environment

Issue



Sometimes called an "Echo Driver", the Mirror Driver is part of pcAnywhere and is used to "mirror" the drawing operations from a Windows machine.

 


Environment



The Mirror driver technology allows for the efficient detection of changes to specific pixels in the display of the Host system. Prior to the implemwntation of this driver, PcAnyhere regularly scanned the entire display for changes. This older method is now referred to as "Legacy mode", and is a more CPU-intensive process than the use of a mirror driver.

 


Cause



The Mirror Driver is based on the Windows XP display driver model. The new Desktop Window Manager in Windows Vista and Windows 7 uses the Windows Vista Windows Display Driver Model that is not supported by the Mirror Driver technology. Therefore, while a mirror driver is active, Windows disables Desktop Window Manager and Windows Aero.

 


Solution



You can permanently disable the Mirror driver by changing the registry key on the host to specify that the backup drivers are used.

Using the pcAnywhere backup drivers will result in a slower refresh rate and a higher CPU overhead. However, the performance impact should not be too high on a well resourced modern system. The performance of the back up drivers can be improved by creating an active window scanning registry key.   Additionally some pcAnywhere features like screen blanking will not work while the mirror driver is disabled.

Advantage of mirror drivers

  • Display is faster

Disadvantages of mirror drivers

  • Requires a restart, as these are kernel drivers
  • Supported on the Windows 2000 and later operating systems.


To Disable Mirror Driver
Disabling the pcAnywhere primary mirror driver via the registry is only recommended for the following purposes:

  1. As a troubleshooting step.
  2. As a workaround for issues that have been found to be caused by or related to the Mirror driver.

The following registry settings will need to be modified on the Host system.

Disclaimer: Symantec ALWAYS recommends backing up any files or folders, especially the Windows Registry before making ANY changes.

32 bit windows Registry Settings.

To modify the registry settings on a 32 bit windows Machine, do the following:

  1. Click on Start > Run. On the open line, type regedit.
  2. Click OK.
  3. Go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\awecho
  4. Change "start" key to 4 (This disables the driver from system load)
  5. Save changes and reboot.

Tweak refresh rate when not using Mirror Driver
To modify the registry settings, do the following:

  1. Click on Start > Run. On the open line, type regedit.
  2. Click OK.
  3. Go to: HKEY_LOCAL_MACHINE\Software\Symantec\pcAnywhere\CurrentVersion\Host and Create a new DWORD entry "ActiveWindowScanning" with a value of 1

64 bit Windows Registry Settings.

To modify the registry settings on a 64 bit Windows Vista Machine, do the following:

  1. Click on Start > Run. On the open line, type regedit.
  2. Click OK.
  3. Go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\awecho
  4. Change "start" key to 4 (This disables the driver from system load)
  5. Save changes and reboot.

Tweak refresh rate when not using Mirror Driver
To modify the registry settings, do the following:

  1. Click on Start > Run. On the open line, type regedit.
  2. Click OK.
  3. Go to: HKEY_LOCAL_MACHINE\Software\wow6432node\Symantec\pcAnywhere\CurrentVersion\Host and Create a new DWORD entry "ActiveWindowScanning" with a value of 1

Thin host uses only backup drivers as quick connect is required, while full Host can use both the drivers depending upon the configuration. Since pcAnywhere mirror driver works in conjunction with the display drivers, it is required to use the correct and latest driver for the video card provided by the manufacturer.

Contact your computer hardware manufacturer for further assistance with video driver updates.




Legacy ID



2008020811293260


Article URL http://www.symantec.com/docs/TECH110005


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