We will be replacing our VNC servers with new hardware running on TOSS4. This bulletin impacts all users who connect to LC via VNC Viewer. VNC users should prepare for the changes explained below.

The new CZ & RZ VNC servers are already accessible for those who want to transition immediately; the current CZ & RZ VNC servers will be turned off on December 15, 2023.

Changes to the SCF are forthcoming and this TB will be updated when we have more info.


As of 12/15/2023, connections to

will route to new hardware on TOSS4. ("Old" VNC hardware is running TOSS3.) This change of hardware and operating system will mean

  • Any sessions hosted on the old server will be permanently deleted.
  • Users will need to upgrade their VNC Client to newest version to take advantage of new features, such as dynamic resolution, and stability fixes.
  • Lustre will be inaccessible from TOSS4 VNCs.
    • VNCs will not directly mount lustre.
    • VNC should therefore be more stable when lustre issues occur.
  • The KDE desktop —including the Konqueror browser — will no longer be available from VNC.
    • We cannot support KDE in TOSS4 because it is not supported by RHEL 8.
    • If you have any custom xstartup files that reference KDE, either these references or the files themselves will need to be removed.

The login procedure for `czvnc` and `rzvnc` will remain the same.

Transitioning early

Sessions on the new VNC hardware can be started prior to 12/15/2023 by connecting to

from VNC Viewer.

During the transition period (now until 12/15):

When you connect to either `czvnc` or `newczvnc` in VNC Viewer, the “Connect to” screen that appears after authentication will offer you pre-existing connections from both `czvnc` and `newczvnc`. You will get error messages or other odd behavior if you try to connect to a session created on `newczvnc` from `czvnc` or vice versus.


All OCF (CZ & RZ) users who use RealVNC’s VNC Viewer to connect to LC systems will be impacted.