In previous Solaris releases, SCSI disk support on x86-based systems was handled by the cmdk driver. In the Solaris 7 release, this support is handled by the sd driver, the SCSI disk driver used on Solaris (SPARC Platform Edition) systems. Although derived from the same code base, there are a few differences between the SPARC and Intel versions in this release. For example, special x86-specific volume label support is provided in the Intel version so applications (which use logical disk names in /dev/dsk) will not be affected by the driver change. The Intel version also provides x86-specific disk geometry support not required in the SPARC version. In addition, ATAPI CD-ROM support is now provided by the sd driver.
For more information, see these man pages: cdio(7I), cmdk(7D), dkio(7I), scsi(4), sd(7D).