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CBT does not track changes correctly on VHDX disks files larger than 2 TB


Veeam Change Block Tracking (CBT) driver incorrectly parses virtual disk file change information causing jobs to failover to “full scan” incremental passes (in case of VSS backup) or to create an empty incremental backup (in case of crash-consistent backup) when both of the following conditions are met:
  1. VHDX file size of a virtual disk is above 2 TB (actual virtual disk capacity is irrelevant).
  2. Hyper-V host version is 2012 or 2012 R2.


Bug in Veeam CBT logic.


Install the following Critical update rollup for Veeam Backup and Replication to address this issue.

More information

Veeam Backup & Replication
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