VMware Backup using Changed Block Tracking failed after upgrading to VMware ESXi 6.0

VMware published a fix for the CBT issue causing VMware backups to fail when using VMware ESXi 6.0 as the hypervisor. So far the workaround was to disable Changed Block Tracking that caused long backup windows.

All customers that were using CBT to backup their VMs after installing or upgrading the ESXi version to 6.0 were affected when taking one of the following actions:

  • Backing up a virtual machine with Change Block Tracking (CBT) enabled fails after upgrading to VMware ESXi 6.0.x on host
  • Backing up a virtual machine with Change Block Tracking (CBT) enabled fails after installing VMware ESXi 6.0.x on host
  • Powering on the virtual machines fails.
  • Expanding the size of a virtual disk fails.
  • Taking virtual machine quiesced snapshots fails.
  • The vSphere Client displays the error similar to:

An error occurred while taking a snapshot: msg.snapshot.error-QUIESCINGERROR

Note: This error may or may not be present

  • In the /var/log/vmkernel.log file located on the ESXi host where the affected virtual machine is running, you see the error similar to:




  • In the vmware.log file of the affected virtual machine, you see an entry similar to:

vcpu-0| I120: DISKLIB-CBT : Creating cbt node 92b78c-cbt failed with error Cannot allocate memory (0xbad0014, Out of memory)

_You can read all about it here – VMware KB article 2114076_

The issue has been resolved with the following patch: 

VMware ESXi 6.0, Patch Release ESXi600-201505001 (2116125)

[optin title="Sign Up for News" text="Get regular news about Virtualization" buttontext="Sign Up" successMessage="Message has been submitted successfully." errorMessage="Failed to send your message. Please try later." invalidEmailMessage="Your email address does not appear valid." border="false" collectfirstname="false" collectlastname="false" collectphone="false" collectcompany="false"]

Metrics and Logs

(formerly, Opvizor Performance Analyzer)

VMware vSphere & Cloud

Monitor and Analyze Performance and Log files:
Performance monitoring for your systems and applications with log analysis (tamperproof using immudb) and license compliance (RedHat, Oracle, SAP and more) in one virtual appliance!

Subscribe to Our Newsletter

Get the latest product updates, company news, and special offers delivered right to your inbox.
Share on twitter
Share on linkedin
Share on facebook
Share on email

Subscribe to our newsletter

White Paper — Registration

We will send you the research paper via email.

CodeNotary — Webinar

White Paper — Registration

Please let us know who you are, so we can send you the CodeNotary Trusted Software Supply Chain white paper.

Become a partner

Start Your Trial

Please enter contact information to receive an email with the virtual appliance download instructions.

Start Free Trial

Please enter contact information to receive an email with the free trial details.