Article number
Affected Versions
Source Hypervisor

FTN-20200601: Zerto Handling of Missing Disk Descriptor Files

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VMware published a knowledgebase article for vSphere 6.7 and vSphere 7.0, whereby disk descriptor files need to be recreated. If vCenter issues a “Cannot open the disk” alert about an ESXi host that has a VRA installed and the alert references a Zerto journal, it is possible that datastores used by Zerto are missing disk descriptor files. Zerto recommends that customers encountering this type of vCenter alert contact Zerto to recreate the missing disk descriptor files.

Target Audience

All Users with vSphere 6.7 and 7.0



In a few cases, Zerto customers running on vSphere 6.7 were unable to power on the VRA VM.  Zerto discovered the below vCenter alert: 

Cannot open the disk 

This vCenter alert indicates that one host with a VRA is missing a disk descriptor file for a Zerto journal vmdk because the vmdk name ends with “log_volume.vmdk” 

VMware has since released a code fix for this issue in vCenter 6.7 U3j and 7.0.1 U1. 

**Note: The above code fix is at the vCenter level. Although VMware best practice is to upgrade ESXi hosts shortly after vCenter, the fix will apply to ESXi hosts yet to be updated as well. Release notes for the fixed version can be found here. **

In the case of a missing Zerto journal volume descriptor file, it is recommended to upgrade vCenter to either 6.7 U3j or 7.0.1 U1. If an upgrade is not possible, Zerto needs to be involved to restore the volume descriptor file to avoid impacting service. 

Recommended Actions to Take 

  • Upgrade vCenter to 6.7 U3j or 7.0.1 U1.
  • If an upgrade is not possible, to prevent journal descriptor files from going missing in affected vSphere/vCenter versions, Zerto recommends shutting down the ZVM prior to a vCenter maintenance restart. The ZVM should remain shut down for 30 minutes after vCenter is back on. This lessens the likelihood of Zerto journal volume descriptor file being affected.
  • In order to quickly recover in the event journal disk descriptor files go missing, back up the descriptor files within the Zerto Volumes folder, which is located on the root of any journal datastore. 
  • Zerto recommends that customers running on affected versions of vSphere 6.7 and vSphere 7.0 that encounter the vCenter alert, and an upgrade of vCenter is not possible, contact Zerto Support to resolve the missing descriptor file issue.  To contact Zerto Support, please open a case by signing into your myZerto Account and mention this field technical notice.