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Question

CBT Restore Issues with VMware – Black Screen After Restore

  • June 30, 2025
  • 4 replies
  • 106 views
J
Novice
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We're encountering a recurring issue related to CBT (Changed Block Tracking) in our VMware environment with Commvault (version 11.36).

After incremental backups fail or complete with CBT-related warnings, any subsequent restore of the affected VMs results in machines that fail to boot — only a black screen with a blinking cursor is shown after powering them on.

In addition, Guest File Restores are no longer possible for these VMs. Attempting to browse the file system results in the following error:
Failed to get items for volume

 

The original VMs continue to run and restart without any issues.

The problem affects multiple servers, not just a single system.

The issue is resolved after performing a full backup — restores (including guest file restores) then work as expected again.

Example error message during backup:

Error code: [19:857]  
Description: SRV-03\SRV-03.vmdk Warning change tracking verification failed,  
             SRV-03\SRV-03_1.vmdk Warning change tracking verification failed  
Source: commserve, Process: JobManager  


Has anyone else experienced this behavior or found a workaround? Any input would be greatly appreciated.

4 replies

S
Vaulter
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Hi ​@Justus_T ,

Good day!

On these scenarios we need to reset the CBT from Vmware end 

https://knowledge.broadcom.com/external/article/339974/resetting-changed-block-tracking-for-vmw.html

If traditional full is added in the schedule that will also reset the CBT

Regards,

Sureshkumar S

 

J
Novice
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  • Justus_TNovice
  • Author
  • Novice
  • July 1, 2025

Hi @Sureshkumar S,

thanks for your reply!

The suggested CBT reset works — we’ve tested it successfully — but unfortunately, this would mean a huge amount of manual effort, since the issue occurs quite frequently across many virtual machines.

That’s why we’re looking for a way to automatically trigger a full backup when this CBT error occurs. We believe that would be a much more efficient and sustainable solution.

What’s strange is that for Error Code 91:461, Commvault automatically triggers a full backup and creates an event in the job history.

But for Error Code 19:857, the job is marked as Completed “without Warnings”, and no event/error is created 

Also, just as a side note: Error Code 19:857 doesn’t even appear in the official documentation here:
https://documentation.commvault.com/2024e/expert/system_messages_event_strings_and_error_codes.html

Any ideas on how to work around this behavior or to automate?

Thanks !

Best regards,
Justus

Rajiv
Vaulter
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  • RajivVaulter
  • Vaulter
  • July 1, 2025

Hi ​@Justus_T Can you confirm if this additional setting is in place on the access nodes? 

Additional Setting: ignoreQuiesceGuestErrors

This can make the job successful and make the job complete successfully. 

Best,

Rajiv Singal

S
Vaulter
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Hi ​@Justus_T ,

We need to look into the vsbkp.log/Vixdisklib.log to understand what we are doing post this warning

SRV-03\SRV-03.vmdk Warning change tracking verification failed

Can you attach the vsbkp.log/Vixdisklib.log which has any sample job to check 

We won't reset the CBT on all occasions/conditions. If needed, you can raise a support case to dive deep into this.

Regards,

Sureshkumar S

 

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