VDP image backups from ESXi 6.0 hosts may lose data written to the VM disk during snapshot consolidation processes
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VDP image backups from ESXi 6.0 hosts may lose data written to the VM disk during snapshot consolidation processes

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Article ID: 327047

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

Symptoms:
During VMware vSphere Data Protection (VDP) operations you experience these symptoms:
  • Restores do not contain all the data that should have been saved by the backup
  • Restores may contain stale data blocks which should have been overwritten with newer data
  • Restored virtual machines exhibit stability issues
  • Restored virtual machines have data missing


Environment

VMware vSphere Data Protection 6.1.x
VMware vSphere ESXi 6.0
VMware vSphere Data Protection 6.0.x

Cause

VMware image backups may be incomplete or may contain stale data blocks in place of new data blocks that were written during snapshot consolidation processes under the combination of the following circumstances:
  • VMware virtual machine is running on an ESXi 6.0 host.
  • VMware virtual machine has CBT enabled.
  • Write operations are performed to the VM disk during snapshot consolidation processes.
Note: The snapshot consolidation process occurs, for example, during the snapshot removal process at the end of every virtual machine backup.

Where this issue occurs, the exact location and extent of the affected blocks in subsequent backups may not be precisely quantified or found. As the number of affected blocks may be low, a test virtual machine backup restore, and a chkdsk or fsck scan may not reveal the issue even if the virtual machine backup was affected. Individual file restores from affected backups may complete most of the time, but the restored data may be incomplete or may contain stale data blocks.

The virtual machine accurately reflects the writes that occurred during the snapshot consolidation process. However, the virtual machine may be impacted by a restore of an affected backup, whether it is to an original, new or existing virtual machine.

Resolution



Workaround:


Additional Information



Impact/Risks: