Backup and Replicas of virtual machines running on ESXi 6.0.x with Change Block Tracking (CBT) enabled may not be recoverable

Veeam Backup & Replication
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Leveraging VMware Changed Block Tracking (CBT) data supplied by VMware ESXi 6.0 can potentially render the data in backups or replicas inconsistent or corrupt.


This is a VMware ESXi issue in CBT logic that affects ESXi 6.0 through ESXi 6.0 Update 1a. It is resolved with VMware ESXi 6.0 patch ESXi600-201511001. Please see VMware KB article for additional information about the issue. 


Installing the patch alone is not sufficient, CBT reset is also required for all of your VMs. CBT reset is mandatory in every scenario, because existing CBT maps may already be inconsistent due to the original bug, which in turn may result in inconsistent full backups in future.

Please follow this article to reset CBT. Please note that performing Active Full backups cannot be considered as a substitute to CBT reset with this particular CBT bug.

More Information

To download the patch, please go the VMware KB article KB2137545

Please be aware that we’re making changes which will restrict access to product updates for users without an active contract.


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