Quiescing Guests

To properly quiesce the guest machines, VMware Tools must be installed and up to date in your Linux/Windows virtual machines.

The quiesce_host=try/yes/no Plugin command line option allows control of how the vSphere Plugin should try to quiesce guest VMs before a snapshot. The default value is try. In this mode, the plugin will try to quiesce the guest when creating the snapshot. If the quiesce operation fails, the plugin will make a second attempt to create the snapshot without quiescing the guest. The first attempt will be reported in the job log as an error and the job termination status will terminate “with warnings”.

FileSet {
  Name = guestvm
  Include {
    # Will try to quiesce the VM and skip the VM
    # from the backup if pre/post scripts are
    # returning an error
    Plugin = "vsphere: host=guestvm quiesce_host=yes"
  }
}

More information about the exact error message can be found in the vSphere console log.

Warning message from ESXi: the guest OS has reported an error during
quiescing. Error code was: 2 the error message was: custom quiesce script
failed.

Or

An error occurred while saving the snapshot: Failed to quiesce the virtual machine.

Linux

By creating a special script located in /usr/sbin/pre-freeze-script, you will be able to quiesce your system automatically when vSphere creates a Snapshot.

The vSphere Plugin will also try to execute /usr/sbin/post-thaw-script script if present on the guest VM.

Windows VSS notes

The plugin enhances Windows protection by performing VSS-based snapshots to quiesce VSS-enabled applications before backup.

VSS Pre-freeze and Post-thaw Scripts

VMware Tools first looks in C:/Program Files/VMware/VMware Tools/backupScripts.d for scripts in alphabetic order, calling them all with freeze argument, and afterward in reverse alphabetic order, calling them with thaw argument (or freezeFail if quiescing failed).