Consistency level parameter (WMI)
This option determines whether or not the I/O on the virtual machine is quiesced before NetBackup creates the snapshot.
Application consistent then crash consistent
NetBackup makes two attempts to quiesce I/O on the virtual machine for an application-consistent snapshot. If both attempts fail to create an application-consistent snapshot, NetBackup creates a crash-consistent snapshot and proceeds with the backup. (See the other two options for a description of application consistent and crash consistent.)
Application consistent
This setting is the default. I/O on the virtual machine is quiesced before NetBackup creates the snapshot. Without quiescing file activity, data consistency in the snapshot cannot be guaranteed. If not consistent, the backed-up data may be of little or no value.
In the great majority of cases, you should accept the default.
Note:
If the virtual machine is in the saved state or the paused state, it cannot be quiesced and the backup job fails. You must use one of the other Consistency level options.
Note these prerequisites for the option:
The latest version of Hyper-V integration services must be installed and running inside the VM.
The Hyper-V integration services must be enabled in the VM settings.
Crash consistent
Caution:
In most cases, Crash consistent is not recommended. With this setting, NetBackup cannot guarantee that all required data has been flushed to disk when the snapshot occurs. The data that is captured in the snapshot may be incomplete.
The snapshot is created without quiescing I/O on the virtual machine. In this case, you must perform your own analysis for data consistency in the backed-up data.