Knowledge Base

Acronis VSS provider is used to initiate creation of VSS snapshot, but MS VSS service is actually used

This article applies to:

• Acronis True Image 9.1 Server for Windows
• Acronis True Image 9.1 Enterprise Server
• Acronis True Image Echo Enterprise Server
• Acronis True Image Echo Server for Windows

Description

Acronis True Image provides technology to automatically utilize Microsoft VSS service to create consistent backups of opened files/folders or databases (in case the database supports VSS technology).

Here is the step-by-step description of how the backup is made with the VSS support option enabled:

1. Acronis True Image initiates VSS snapshot. This snapshot is created by MS VSS service via Acronis VSS provider, which is in fact a 'fake' VSS provider. Acronis True Image must start VSS snapshot creation through Acronis VSS provider to capture the moment when all VSS writers freeze and databases are ready for backup. This is the only purpose of Acronis VSS provider, e.g. VSS snapshot created in this step is not used at all and is in fact a 'fake' one. It was necessary to create this 'fake' VSS provider because MS VSS service does not have API functions to freeze VSS writers directly;
2. Acronis True Image sends a request to MS VSS service to suspend VSS writers;
3. Acronis True Image creates a simple snapshot (not a VSS snapshot). This snapshot is created when all writers freeze and databases are ready to be backed up;
4. Acronis True Image aborts VSS snapshot initiated by MS VSS, as this snapshot is not necessary. This may result in errors in the Windows Event logs, which can be safely skipped. Please take a look at the sample log from Event Viewer with similar errors;
5. Acronis True Image initiates a backup through the simple snapshot created in step 3.

More information

See also Microsoft TechNet Article: What Is Volume Shadow Copy Service?

Sample scenario

1. Run Acronis True Image local version on a machine with Microsoft Volume Shadow Copy Service;
2. Click Backup to run the Create Backup Wizard;
3. On the Choose Backup Options screen select Set the options manually;
4. On the Backup Creation Options screen under Database support select Volume Shadow Copy Service;
5. Select Microsoft VSS support;
6. Click Next and proceed with the backup.

See also:

• Backing Up a System with VSS (a step-by-step guide)
• Domain Controller Cannot Start after Restore
• VSS Log Files