Parallels

Resolution

Virtuozzo 4.0 comes with the support of the Microsoft Volume Shadow Copy Service (MS VSS) technology allowing you to use third-party backup applications for creating Virtual
Environment backup archives.

To provide the integration with VSS, a special writer service - Virtuozzo VSS Writer Service - has been implemented. Like any other VSS writer, the Virtuozzo VSS writer ensures that, during backup operations, all data are in the persistent and stable state. In addition to this, it creates one VSS component for each Virtual Environment on the Hardware Node. Any VSS component has control over the following VE-related files on the Node:

 - all the files located in the X:\vz\private\VE_ID folder and
 - the VE_ID.conf and VE_ID.conf.bak files in the X:\vz\Conf folder.

Currently, you can use the following third-party tools to perform VE backups:

 - NTBACKUP built in Windows Server 2003;
 - EMC Networker, version 7.3;
 - Symantec Backup Exec 11d for Windows Servers;
 - IBM Tivoli Storage Manager, version 5.3;
 - BrightStor ARCserve Backup r11.5 SP2 for Windows.

A typical process of creating VE backups on the Hardware Node using any of these tools is
described as follows:

1. The backup application requests a list of VSS components from the Virtuozzo VSS Writer Service.

2. The Virtuozzo VSS Writer Service provides the requested components list (i.e. one VSS
component per VE).

3. The backup application transmits the list of volumes to take part in the backup process to the Virtuozzo VSS Writer Service and asks it to freeze its activity.

4. On the basis of the received volumes list, the Virtuozzo VSS Writer Service makes a list of running Virtual Environments for backing up and forces the MS VSS services inside the
affected VEs to freeze all VSS writers, which results in the suspending the activity of all
VSS-aware applications inside these VEs (MS SQL Server, MS Exchange Server, etc.).

5. The MS VSS service on the Hardware Node creates a shadow copy of the volumes to be
backed up.

6. The backup application makes a backup of the VE files from the shadow copy.

7. After the backup creation, the backup application asks the Virtuozzo VSS Writer Service to resume its activity. It its turn, the Virtuozzo Service transmits the received signal to the
corresponding Virtual Environments, thus, allowing the VE VSS services and VSS-aware
applications inside the VEs to resume their activity.

Although the concept underlying the creation of VE backups using the VSS technology is the same for all third-party applications listed above, each application demonstrates a number of peculiarities which should be taken into account when making VE backups.

Detailed information on these peculiarities is provided in Virtuozzo User's Guide.