The upcoming Daylight Saving Time adjustment on Sunday November 5th at 2:00 AM (EST) can cause synchronization and operational issues in VDI environments. Machines, especially those using Citrix and VMware services, may experience time discrepancies leading to registration issues, session disconnects, and policy failures. To mitigate potential disruptions, it’s essential to update the base image of your non-persistent machines promptly after the time change.
The semi-annual time change can cause major problems in VDI environments, including machine registration issues, session disconnects, and group policy failures. Whether you’re using Citrix Provisioning Services, Citrix Machine Creation Services, or VMware Horizon View Linked/Instant Clones, non-persistent machines revert to the base image every time they reboot. After the shift from Daylight Saving Time, the clock on these machines will be off by 1 hour every time they restart until the base image is updated to the correct time. As a result, the machine’s system clock will not match the time in the Windows Domain for a brief period after a reboot. This discrepancy can lead to issues obtaining IP addresses and authenticating with Domain Controllers, causing a variety of problems within the desktop and user environment.
Potential side effects include:
- Errors in applying machine Group Policies
- Errors when logging into the domain
- Login scripts not executing
- Errors in acquiring/renewing IP addresses from DHCP
- Communication problems with virtual desktop agents
- Failed user connections
- Unregistered machines
Once the machine has operated for a while, the clock will adjust, domain authentication will succeed, and machine policies will apply (assuming background processing of Group Policy is enabled in your domain). However, it’s the period right after a restart that can be problematic, leading to unusual behavior and even service failures. Be aware of this issue and consider updating your base image, as it’s the only complete solution to this problem.
For further reference on both VMware Horizon and Citrix Virtual Apps and Desktops, check out the links below:
The severity and impact of these issues can vary based on numerous factors in the environment. For instance, DHCP lease times and whether Group Policy delivers crucial settings to machines at startup can affect the outcome. Without these settings, machines might not register or function properly. While many environments might run without noticeable issues despite the initial clock discrepancy, the only way to ensure no problems arise is to update the base image after the time change.
Plan to update your image(s) and, at the very least, thoroughly test your VDI systems on Sunday morning after the time shift to prevent disruptions on Monday.
Should you have any questions or require assistance during this transition, feel free to contact us at service@helient.com.
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