One of the key features of Solaris 10 is the new ZFS (Zettabyte File System). The new Solaris 10 06/06 update 2 (release notes is the first of the open releases to support a stable version of ZFS.

ZFS itself covers two aspects of data storage, first it treats all physical volumes logically (which means you gain the potential for features like redundancy, or aggregation of multiple devices into a larger resource) and then it treats all filesystems as virtual (which means you can create a filesystem to the size you want, across all available logical volumes).