ResolutionParallels Virtuozzo Containers 4.5 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 a 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
- 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, which comes built-in with Windows Server 2003 (on x64 nodes only)
- EMC Networker, version 7.4.3 Service Pack 3 (on x64 nodes only)
- Symantec Backup Exec 12.5
- IBM Tivoli Storage Manager, version 5.5
- IBM Tivoli Storage Manager, version 6.1 (on x64 nodes only)
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 suspends 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, thereby 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 the Virtuozzo User's Guide.
For a list of supported third-party backup solutions in PVC 4.0, refer to this KB article.