This article describes the possible causes and solutions for screenshot failures with a completely or partially blank screen.
- Datto SIRIS
- Datto ALTO
- 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 the 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 Device GUI. Adjust the amount of time the virtual machine needs to wait before taking a screenshot using the Screenshot Verification drop-down.
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. The default Windows power setting turns off the screen after 10 minutes of inactivity. Long Additional wait times may exceed this threshold. Setting this threshold to "never" will resolve the issue.
5. Start a backup for the production machine. Wait for the backup to complete.
6. Force a new screenshot verification, and observe the results.
ALTO devices use hybrid virtualization to launch VMs in the cloud, rather than on the local device. However, the screenshot is produced on the local device. This makes timing the virtualization launch, as outlined above, an unreliable method of estimating additional wait time for ALTO devices. We recommend testing screenshots with varying additional wait times to determine the additional time required.
If adjusting the verification and screensaver times does not resolve the issue, you can change the Virtualization Video Controller to the 'Cirrus' setting. This setting is found on the Remote Web, at Protect → Configure Agent Settings → Advanced.
Figure 4: Virtualization Video Controller selector (click to enlarge)
If the production machine has pending Windows updates, this state will be replicated to all snapshots taken of it from the time the updates became available until the time that they are installed. This can cause screenshots of the protected system to appear blank, because the pending Windows updates are attempting to install in the virtual environment, causing the boot process of the screenshot VM to take longer than usual to complete.
To correct this issue, you can install the pending Windows updates on the production machine and take a new backup. Alternatively, you can increase the Additional Wait Time setting for the protected system to allow the agent more time to boot fully before your Datto appliance attempts screenshot verification.
Dell Data Protection
Dell Data Protection (external link) may cause failed screenshots showing a blank screen and a cursor. If this service is enabled on the production machine, attempt another backup after disabling it.