Problem Description:
Time drift is observed in the guest operating system of virtual machines when backups are performed with the "quiesce" option enabled. Despite this issue, the backup jobs complete successfully without reporting any errors.
Cause:
The guest operating system experiences a time drift due to virtual machine stunning during the snapshot consolidation process. During backups, the backup proxy interacts with VMware APIs, while VMware manages snapshot creation, removal, and consolidation. The proxy performs read operations on the snapshot disks and does not access the guest operating system of the virtual machine unless App-aware backups or UDA scans are enabled.
Resolution:
To mitigate time drift in the guest operating system, consider the following options:
Enable Time Synchronization in VMware Tools: Ensure that time synchronization is enabled within VMware Tools to keep the guest OS clock aligned with the ESXi host.
Use Network Time Protocol (NTP): Configure the guest operating system to synchronize time with an NTP server to maintain accurate system time.
Disable Quiescing for VM Snapshots: If time drift is a critical concern, you may choose to perform snapshots without quiescing the VM, though this could impact application consistency.