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Virtual Machine is not responding when running a backup

We have been noticing some alerts saying Virtual Machine is not responding when running a Virtual Machine level backup. Customers were complaining about the application unavailability and they were getting some alerts saying Virtual Machine is not responding or down state at the same time of everyday. This issue appeared due to the FREEZE operation on the file system.

We have tried several troubleshooting steps to find a solution for this and had to spent considerable amount of time on the same issue, unfortunately we were continuously getting the same “Virtual Machine is not responding” alert from the monitoring. Finally, we were able to find a solution after performing the below steps separately for Windows and Linux Virtual Machines.

Note : VMware Tools must be installed and should be up to date. See how to install VMware Tools on a Linux machine in this article.

Virtual Machine is not responding: VMware Tools status

Virtual Machine is not responding ? This is the workaround for the Linux Virtual Machines

Connected to the ESXi host which was running the affected Linux Virtual Machine and changed the directory to the Virtual Machine folder.

#cd /vmfs/volumes/<datastore_name>/<Virtual_Machine_folder>

Virtual Machine is not responding: Change Directory

Checked disk.EnableUUID setting is in the .vmx file

/vmfs/volumes/<datastore>/<virtual_machine_folder>/#cat virtualmachinename.vmx | grep disk.EnableUUID

Virtual Machine is not responding: Check EnableUUID

In my case this parameter did not exist, so I had to edited the .vmx file using a text editor, added the disk.EnableUUID parameter and set it as “FALSE”, if you can see the parameter in your .vmx file, set the value to “FALSE”. (I used “vi” editor and “:wq” used to save the parameter).

Confirmed the parameter addition using the same command

After the completion of the parameter addition logged in to the Operating system of the Virtual Machine and changed the directory to “/etc/vmware-tools/” folder and check whether there is “tools.conf” file is there, if it id not there then create a file. In my case we had to create the file.

#cd /etc/vmware-tools/

To create the file used vi editor

#/etc/vmware-tools/vi tools.conf

Added the below content to the file, save it and exit

enableSyncDriver = false
vmtoolsd.level = debug
vmsvc.level = debug
vmusr.level = error
vmvss.level = debug
guestinfo.level = error
vix.level = error

Note: This only runs a sync operation before the snapshot, and does not run a FREEZE on the filesystem.

Virtual Machine is not responding ? This is the workaround for the Windows Virtual Machines

If it is a Windows Virtual Machine you might need to check the Windows Application logs to identify whether there are errors related to the VSS Writers. In some cases VSS Writers may having some issues and had to exclude the VSS Writers from the snapshot operation. A sample issue can be seen in this Microsoft article, you might be seen something similar to these symptoms.

To find the VSS Writers run a Command Prompt with the Administrative privileges and run the below command

C:\Windows\system32>vssadmin list writers

Read more about VSSAdmin Utility from Microsoft Documentation.

Then opened the “%ALLUSERSPROFILE%\Application Data\VMware\VMware Tools\” location in the explorer

Created a “vmbackup.conf” file, to do that opened a Notepad added the VSS Writer and saved it as a configuration file. See below screen captures for more information

Created the “tools.conf” file in the same location and added the below content

log = true
vmtoolsd.level = debug
vmtoolsd.handler = file
vmtoolsd.data = C:\ProgramData\VMware\VMware Tools\vmtoolsd.log
vmusr.level = error
vmvss.level = error
guestinfo.level = error
vix.level = error

You should be able to see something similar to this after the creation of the file

Restarted the VMware Tools Service

After doing these configuration changes to the .vmx file and the .conf file of the affected Virtual Machines this issue was resolved and Virtual Machines are not freezing during the backup operation. I hope you will not be seeing “Virtual Machine is not responding” alert in your environment after following these steps.

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Aruna Fernando

"Sharing knowledge doesn't put your job at risk - iron sharpen iron" I heard this and it's true.

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