IBM Tivoli Storage Manager failed to create the backup because of the mixture of volumes was detected. Some volumes selected meet the requirements for importing snapshots only when needed and some do not. This situation occurs when a backup operation is requested and the "Import VSS snapshots Only When Needed" feature is enabled and not all the volumes involved in the backup operation are managed by a VSS Hardware Provider that supports transportable snapshots. Additionally the situation can also occur in a clustered environment during a backup operation, when not all the volumes involved in the backup operation are managed by a VSS Hardware Provider that supports transportable snapshots.