If you do not set the slice option, a file or volume is exported as a full disk. In that case, virtual disk drivers (vds and vdc) forward I/O from the virtual disk and manage the partitioning of the virtual disk. The file or volume eventually becomes a disk image containing data from all slices of the virtual disk and the metadata used to manage the partitioning and disk structure.
When a blank file or volume is exported as full disk, it appears in the guest domain as an unformatted disk; that is, a disk with no partition. Then you need to run the format(1M) command in the guest domain to define usable partitions and to write a valid disk label. Any I/O to the virtual disk fails while the disk is unformatted.
Prior to the Solaris 10 5/08 OS release, when a blank file was exported as a virtual disk, the system wrote a default disk label and created default partitioning. This is no longer the case with the Solaris 10 5/08 OS release, and you must run format(1M) in the guest domain to create partitions.