This article describes the cause and possible solution for screenshot failures with a completely or partially blank screen.
Figure 1: Example of partial black screen boot
- The operating system is not waiting long enough to load before attempting to capture a screenshot.
- The operating system is waiting too long to load before attempting to capture a screenshot, and the virtualization's GUI is going into a power-saving state.
- The operating system's screensaver is turning on, preventing a capture of the operating system in a ready state.
1. Mount a local virtualization of the affected server from the Datto appliance's GUI. Set the virtualization's resource allocation to 1 CPU core and 2 GB of RAM. Start the virtualization, and observe the amount of time the VM takes to boot to the Windows login screen.
2. If the production machine has a screensaver configured, observe the amount of time it takes for the screensaver to turn on in the VM.
3. Stop and unmount the virtualization. Navigate to the Protect → Configure Agent Settings tab of the Datto GUI. Adjust the amount of time the virtual machine needs to wait before taking a screenshot using the Screenshot Verification drop-down shown in Figure 2.
Figure 2: Screenshot Verification Schedule Options
4. Adjust the screensaver wait time on the production machine to allow enough time for the virtualization to boot, and for the Datto appliance to capture a screenshot.
5. Start a backup for the production machine. Wait for the backup to complete.
6. Force a new screenshot verification, and observe the results.
If adjusting the verification and screensaver times does not resolve the issue, you can change the Virtualization Video Controller to the 'Cirrus' setting on Datto appliances running Ubuntu 16.04. This setting is found on the Remote Web, at Protect → Configure Agent Settings → Advanced, as shown in Figure 3.
Figure 3: Virtualization Video Controller selector