This document introduces how to adjust the resolution of the instance login via VNC through the CVM console.
If Windows system images have very low VNC resolutions, some applications may fail to be properly displayed or opened. To avoid these issues, you need to modify the resolutions of Windows system images.
Some Linux system images have lower VNC display resolutions by default. For example, the VNC resolution for CentOS is only 720 * 400. You can set the VNC resolution to 1024 * 768 by modifying the parameter grub.
Note:
More recent Linux images such as CentOS 7, CentOS 8, Ubuntu, and Debian 9.0 adopt a default VNC resolution of 1024 * 768, which can be used without any modifications.
Prerequisites
You have logged in to the instance via VNC. For details, see the following documents:
The steps below describe how to modify the VNC resolution of a Windows instance on the Windows Server 2012 operating system.
For Windows images using the UEFI boot mode, if the qxldod driver is not installed, the VNC resolution cannot be adjusted. You can install the driver by accessing the directory containing qxldod.sys through the command line and running the command pnputil -i -a qxldod.inf. After successful installation, the VNC resolution can generally be adjusted without requiring a reboot.
Note that after this driver is installed, the VNC mouse pointer may appear as a small square, affecting the visual appearance but not the normal usage. The qxldod driver is optimized based on the upstream open source community. If you are concerned about the mouse pointer issue, it is recommended to select Windows images using the Legacy BIOS boot mode.
1. Right-click on the desktop and select Screen resolution, as shown below:
2. In the “Screen Resolution” window, set Resolution to your desired value and click Apply, as shown below:
3. In the pop-up window, click Keep changes.
4. Click OK to close the “Screen Resolution” window.
The steps below describe how to modify the VNC resolution of a Linux instance on the CentOS 6 and Debian 7.8 operating systems.
CentOS 6
A CentOS 6 image has a VNC resolution of 720 * 400 by default. To set its resolution to 1024 * 768, modify the launch parameter grub as follows:
1. Run the following command to open the /etc/grub.conf file.
vi /etc/grub.conf
2. Press i to switch to the editing mode, and add vga=792 to the parameter grub, as shown below:
3. Click Esc and enter :wq to save and close the file.
4. Run the following command to restart the CVM.
reboot
Debian 7.8
Both Debian 7.8 and Debian 8.2 images have VNC resolutions of 720 * 400 by default. To set their resolutions to 1024 * 768, modify the launch parameter grub as follows:
1. Run the following command to open the grub file.
vim /etc/default/grub
2. Press i to switch to the editing mode and add vga=792 to the end of the parameter value GRUB_CMDLINE_LINUX_DEFAULT, as shown below:
3. Click Esc and enter :wq to save and close the file.
4. Run the following command to update the grub.cfg file.
grub-mkconfig -o /boot/grub/grub.cfg
5. Run the following command to reboot the CVM.
reboot
Appendix
The VGA parameter values corresponding to different Linux instance resolutions are listed below:
