The volumes are not shared.

For offhost backup to work, all volumes must reside on disks that are shared between the remote computer and the Backup Exec media server. It is the backup administrator's responsibility to confirm this. If the volumes are not shared, the import operation will fail, and you may need to clean up the snapshots and resynchronize the volumes manually.

The VSS provider is not installed on the media server and the remote computer.

The provider used for snapshot must be installed on both the media server as well as on the remote computer. If the provider is not installed on the media server, the import operation will fail, and you may need to clean up the snapshots and resynchronize the volumes manually.

All volumes are not transportable.

All volumes selected for backup must be transportable to the media server. If Microsoft SQL or Exchange, or other database applications are selected for backup, make sure that the databases and log files reside on transportable volumes.

The VSS provider cannot snap all of the selected volumes.

In addition to being transportable, all volumes selected for backup must be snappable by the same provider. It is the backup administrator's responsibility to ensure that all volumes in a backup job are supported by the same VSS provider.

The log path location is incorrect.

Log files created by the provider or by its supporting application during normal snapshot operation should not reside on any of the volumes being snapped. This prevents VSS from flushing the write buffers, and the snapshot will time-out. Change the log path to another volume.

The provider or VSS services are not started

Make sure that the provider service is running and make sure that the Microsoft Windows "Volume Shadow Copy" service has not been disabled.

The credentials are incorrect.

Make sure that the machine-level credentials used for the job are the same on both the media server and the remote computer. Incorrect credentials will cause snapshots or the backup to fail.

The VSS provider is not installed on all media servers in a Central Admin Server Option (CASO) environment.

If a backup job is configured in a CASO environment, you must target the job to media servers on which the selected VSS provider is installed rather than allowing the job to be delegated by the central administration server. Otherwise, the job could be delegated to a media server that does not have offhost capability.

See How to use media server pools in CASO .

The media server and the remote computer are in the same cluster group.

When performing an offhost backup in a Microsoft Cluster Server (MSCS) or Veritas Cluster Server environment, the media server and the remote computer must not be in the same cluster group. The cluster applications cannot support devices' logical unit numbers (LUNs) that have duplicate signatures and partition layouts; therefore, the snapshots containing the LUNs must be transported to a media server that is outside the cluster in which the host cluster resides.

If you are using an Hitachi 9970 and attempt to protect a Microsoft Cluster Server (MSCS) resource using the Advanced Disk-based Backup Option (ADBO), you may receive the following error message:

The job failed with the following error: A failure occurred 
querying the Writer status.

To correct this problem, ensure that the RM Shadow Copy Provider for Volume Snapshot Service is present and running. If the service is not running, run RMVSSPRV.exe from c:\horcm\tool. If the service is still not running, contact Hitachi for support.