VMware is actively working to address a recently discovered issue wherein an incremental backup becomes a full backup when backing up Windows 2008 (or higher) virtual machines with VSS-based application quiesced snapshot.
This recent CBT (Changed Block Tracking) issue does not cause any data loss or data corruption.
This issue is well understood and VMware engineering is actively working on a fix.
For more details on this issue and latest status on resolution, please refer to KB article: After upgrading to ESXi 6.0 Build 3825889, incremental virtual machine backups effectively run as full backups when application consistent quiescing is enabled (2145895)
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