What's the latest status of this BZ?
The reference in the doc says, "Separate vmstore and data volumes are recommended to minimize backup storage requirements. Storing virtual machine data separate from operating system images means that only the data volume needs to be backed up when storage space is at a premium, since operating system images on the vmstore volume can be more easily rebuilt. ", which clearly explains the need for separate 'vmstore' & 'data'
Will that change also happen in single node deployment guide ?