Certain embodiments described herein relate to an improved selective data backup system. In some embodiments, one or more components in an information management system can determine that a portion of the primary data scheduled for backup was previously backed up or is scheduled to be backed up as part of another backup operation. For example, a data agent performing a cluster-level backup operation for an entire cluster of storage servers may check whether any part of the primary data was previously backed up by a prior server-level backup operation for one of the storage servers in the cluster. If so, the data agent may skip, in the cluster-level backup operation, any portion of the primary data stored in the storage server previously backed up as part of the prior server-level backup operation.