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Question

Webservers fail VM quiescing

  • 15 December 2022
  • 4 replies
  • 102 views

Hi, we’re going through our VM backups in regards to the VMs that fail to quiesce during snapshot operation. We can see a pattern where many of these VMs are running some Apache or IIS webserver.

I’m wondering if that might be due the webserver are running some kind of database that might be causing the issues? Maybe like SQL express or MySQL.

For regular and full blown SQL servers we disable the “SQL Server VSS writer” to stop the snapshot interfering with the SQL log backup chain and that normally solves the quiescing issue.

Anyone that has some insight to this perhaps? I would like to avoid using agent backup if possible.

If you have the quiescing option enabled on the VM group than Commvault will try to perform the quiesce operation. If it runs into an issue than it will report the failure and for Windows it will leverage VSS which in your case is disabled hence there is a big chance that this is the root cause. I would perform a test on one instance to enable VSS on one instance and run an on-demand backup job. 

I’m not sure what you mean with instance? Is that related to the webserver application itself or?

We see this issue with both IIS and Apache webservers. At least that is the pattern for most of the VMs that can’t be quiesced during snapshot operation.

I have tested with a server that is having issues and an agent backup completed with no issues so VSS is working in general I would say.

Thanks.

@JQEI well it depends if the agent is configured to perform a VSS snapshot, but if you stop the VSS services than you can bet on it that it is unable to perform an application level quiesce. 

What is je error stating? Have you gone through the logs? 

Agent is configured to use VSS so VSS is working in general I would say.

The issue with webservers is widespread. However, we also have VMs running webserver application that can be quiesced. But it looks like those might be running a full blown SQL server where the SQL Server VSS writer service is disabled.

Again that’s why I’m suspecting that issue is caused by some SQL express or MySQL application that’s preventing the quiescing of the VM.

I raised a case to Commvault but they couldn’t help much. They only provided this:

quiescing is a VMware feature. From our side, I have already provided the known causes. I would suggest the question should be asked to VMware Support for other reasons that cause the quiescing issues and we might not be aware of them.

We have checked the basic things as VMtools running and VSS writers.
The error in CV is: Description: STGCognos002 Failed Unable to quiesce guest file system during snapshot creation
When trying same operation from VM level it also fails.

I have asked my VM team to check with VMware but they say they don’t have support for this.

I only have access to Commvault and I don’t know if there’s any log that can tell more about the specific issue. If there was I would assume that Commvault Support has checked this as part of the case I had with them.

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