Application Aware Backups (8.0)


Steps for creating application-consistent backups


In version 8.0 and later, you can create application-consistent backups, including properly quiescing applications before backup and performing required post-backup processing tasks, such as log truncation for MS Exchange..

Note: To perform quiesce and to run custom scripts for VMware, both vCenter and the guest hosts must be vSphere version 5.0 or later.

Application aware options are enabled when you create the backup job. They are enabled per-VM in the Job Inventory table in the first step of the Backup Dialog. In addition to Quiesce and Log truncation, you have the option to perform additional tasks after a backup is complete by running custom scripts. For details, refer to the article Running Custom Scripts After a Backup.


Figure - Application Aware options in the Backup Dialog's Job Inventory Settings table

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Quiescing Virtual Machines

Unitrends Virtual Backup can create transactionally-consistent backups for VMs running applications that are VSS-aware. By taking advantage of Microsoft's Volume Shadow Copy Service (VSS), Unitrends can initiate quiesce for any VSS-aware applications running on the virtual machine to ensure an application-consistent backup is created. 

When an application aware backup is started, UVB initiates the quiesce process and an application-consistent VSS snapshot is created on the VM. The backup process continues and writes the data to the backup store. When the backup process completes, the VSS snapshot is removed.

Quiesce is enabled per-VM when you create the backup job. After selecting a VM for backup, use the Job Inventory table in the Backup dialog to enable quiesce for your VMs.

Quiesce is supported for the following Windows operating systems:

  • Windows Server 2008 and 2008 R2
  • Windows Server 2012 and 2012 R2


Log Truncation - Microsoft Exchange

Note: Log truncation is supported for Hyper-V and VMware virtual machines running Microsoft Exchange on Windows 2008 Server and later

If you are running Microsoft Exchange, you can perform log truncation after the backup has completed. Log Truncation can be enabled in the Backup Dialog's Job Inventory Settings table for each individual virtual machine. After enabling Log Truncation, UVB will initiate the VSS snapshot process and create two files on the guest VM. Credentials with appropriate permissions are required - these can be configured using the Protect page, Settings tab for each VM. You have two options when configuring Log Truncation - Always, in which case logs will be truncated every time a backup is run regardless of the result and After Successful Backup, in which case truncation occurs only after a backup completes successfully.

After the files are copied to the user's temp directory and the VSS snapshot is created, the backup continues. When the backup completes, the log truncation occurs for Exchange and the files are removed. Note that if the backup fails, log truncation will not occur.

Note: Log truncation uses diskshadow.exe. To allow the appliance to run this application, Admin Approval Mode must be disabled on the Exchange server as described in: Configuring your server for Exchange log truncation.


Log Truncation - Microsoft SQL Server

To perform log truncation for Microsoft SQL Server, you can use custom scripts to send the commands required to your SQL Server database. Example scripts are available for download at the link below, along with instructions for modifying those scripts, to enable log truncation for SQL Server.


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