Article number
Affected Versions
Source Hypervisor

Zerto Field Notice FTN-20200601: Zerto Handling of Missing Disk Descriptor Files

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Date: 6/1/2020

Field Technical Notice: FTN-20200601 

Zerto Version Affected:

  • All versions on vSphere 6.7 and vSphere 7.0 


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.  


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” 

In the case of a missing Zerto journal volume descriptor file, Zerto needs to be involved to restore the volume descriptor file to avoid impacting service. 

Recommended Actions to Take 

To prevent journal descriptor files from going missing, 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 vSphere 6.7 and vSphere 7.0 that encounter the vCenter alert, 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.