Message: "One or more of the VSS Writers required for backup type are missing"

Summary:

Carbonite Safe Server Backup utilizes a Windows feature known as Volume Shadowcopy Services (VSS) to create snapshots of data for backup. Most backup types have a designated VSS Writer that is explicitly dedicated to backup and restore of that specific data type. For example, there is an SQL Server Writer that is used for backup and restore of Microsoft SQL Server databases.

Some backup types have a single writer; others have multiple writers. Every writer is controlled by a Windows Service.

The VSS Writers are used by many different applications. Nearly all Windows backup applications (including CSSB) utilize the VSS Writers but they aren't used exclusively for backups; for example, the System Restore functionality in Windows uses VSS to create restore points that allow users to roll back to a known good configuration.

Cause:

A CSSB backup may fail and report the error, "One or more of the VSS Writers required for <backup type> are missing."

The <backup type> field will populate with the type of backup set for the failed backup. For example, if the error appears when running a System State backup, the error would say "One or more of the VSS Writers required for System State are missing."

A list of VSS Writers will be shown after the error message. Internal log files will show the error code: ZWC_ENG_ERR_NO_WRITER_DATA

More Information

This error occurs when one or more of the writers required for backup is missing or not available. A writer is considered "missing" when it is not listed after running the vssadmin list writers command. If a writer is missing, all backup operations that utilize that writer will fail.

A missing writer is a failure of the Windows operating system. The writer may be corrupted, in a catastrophic error state, not installed on the system, disabled, or otherwise damaged in some way.

A missing writer is notably different from a failed writer. If a writer has failed, please see Error: One or more of the VSS writers required for backup have failed.

Backups will continue to fail until the writer is properly listed when running the vssadmin list writers command. Run vssadmin list writers from an elevated (Run As Administrator) Command Prompt.

This article applies to:

Carbonite Plans	Products	Platforms
Power and Ultimate (Not sure?)	Carbonite Safe Server Backup (Not sure?)	Windows

Solution:

First, refer to the Carbonite Server User Guide and ensure that all requirements for backup are met. Some backup types require that the Windows System Administrator enable or register the appropriate VSS Writers.

Next, ensure that the Windows operating system and the databases or applications pending backup are fully up to date via Windows Update. Microsoft has released many VSS-related hotfixes (including several that resolve missing VSS Writers).

Finally, some circumstances leading to missing VSS writers are more common than others. Please refer to the articles below for more details. These articles are intended to be a general guide and represent only the most common causes for missing VSS writers.

• Microsoft SQL Server: The SQL Server Writer can go missing if one or more database contains a space in its name. Please refer to Troubleshooting SQL VSS Writer Issues for more information.
• System State: If the System Writer used for Windows System State backups is missing on Windows Server 2008, please see System State Backups Fail and the System Writer is Missing.
• Microsoft Exchange Writer: The Exchange Writer is disabled by default in Windows Small Business Server 2003. Enable the writer.

To reiterate, a missing VSS writer is a failure of the Windows operating system. It is the responsibility of the Windows System Administrator to resolve any circumstances that result in a failed or missing VSS writer. Carbonite Safe Server Backup cannot back up data until the VSS writers required for each type of backup set are properly listed and available on the system.