You use volumes to increase storage capacity, performance, and data availability. In some instances, volumes can also increase I/O performance. Functionally, volumes behave the same way as slices. Because volumes look like slices, they are transparent to end users, applications, and file systems. Like physical devices, volumes are accessed through block or raw device names. The volume name changes, depending on whether the block or raw device is used. See Volume Names for details about volume names.
You can use most file system commands (mkfs, mount, umount, ufsdump, ufsrestore, and so forth) on volumes. You cannot use the format command, however. You can read, write, and copy files to and from a volume, as long as the volume contains a mounted file system.