Checking and setting Change Block Tracking for VMware image backups

One of the most common backup issue I see when backing up VM images is that change block tracking in not set.  If it is not Avamar has to parse the entire vmdk file to find the changes causing the backups to run long, it puts a large load on the server and storage during the process.  Using change block tracking greatly improves VM image backup time. To ensure Avamar is using the feature, you must both check the option when you add the client as one that will be baked up and ensure it is turned on in VMware.

You can validate it's enabled on your VMs by using proxycp.jar

java -jar proxycp.jar --cbtstatus  | grep -E "VM Name|CBT"
add the --vm VMname flag to check a single server

If you would like to try and enable it on all VMs:
java -jar proxycp.jar --cbtstatus --enablecbt

This will cause Avamar to attempt to enable it on all VMs it has registered. If the VMware hardware level is too low to support CBT it will just error out in VMware.