NNM GUI Problems on UNIX Systems

The X-Window system on the user’s UNIX workstation must be properly configured for pain-free operation. A common complaint is that a GUI, usually ovw, cannot connect to the display. This may be caused by an incorrect or unset $DISPLAY variable, insufficient permissions to connect to the display (xhost + fixes this), the name of the display cannot be resolved using the local DNS resolver, or there is no IP route between the NNM system and the workstation running the X-Windows emulator.

An active ovw session may be abruptly terminated because the user’s workstation locked up, the user exited the X-Windows environment ungracefully, or the X-Windows emulator locked up. Sometimes this type of failure is not communicated to the ovw session, which continues to attempt I/O to its display. On unpatched NNM systems this may result in a spinning ovw session which may consume an entire CPU. The spinning process must be terminated manually, either by its owner or by root. ITO can be programmed to monitor for this behavior and to execute the termination command (a kill -9 ovw_pid).

If the physical size of the monitor is too small, then some of the taller GUIs cannot display in their entirety. This may result in missing buttons at the bottom of the window. It’s recommended that a 1280x1024 monitor be used, or at least a virtual screen of that size should be available that can be panned when the physical dimensions of the monitor are less than recommended.

Font problems sometimes occur because the X-Windows emulator installation does not include the necessary fonts. A possible fix is to perform a full install of the software, or to upgrade to the most recent version. A second fix is to configure an X-Windows font server on the network and configure the X-Windows emulator to use it. A work-around is to examine the application defaults file for the application, look for font resources, identify available substitute fonts, create an X-Windows application resource_file in the user’s home directory configuring these new fonts, and use the xrdb resource_file command to activate the resources. The application will use the substitute fonts next time it is invoked and cease issuing font warning messages.

Color problems may occur when ovw executes on a display whose public color map has insufficient free colors. This seems to happen often when a web browser is already running when ovw is launched. The fix is to exit the browser and any other applications that use a lot of color before executing ovw.

Finally, there may be performance problems with the NNM GUI. This may stem from a lack of available resources on the workstation, starving the X-Windows emulator of needed RAM, CPU cycles, or TCP sockets. Try quitting some applications to free up RAM and CPU cycles, and configure the X-Windows emulator to use more TCP sockets (the default limit may only be 16, which is generally inadequate for NNM use).