A group of physical slices accessed as a single logical device by concatenation, striping, mirroring, setting up RAID5 metadevices, or logging physical devices. After they are created, metadevices are used like slices. The metadevice maps logical block addresses to the correct location on one of the physical devices. The type of mapping depends on the configuration of the particular metadevice. Also known as pseudo, or virtual device in standard UNIX terms.

a virtual disk created from many physical disks and available for applications as one disk

A group of physical slices (disk partitions) that appear to the system as a single logical device. Metadevices are pseudo, or virtual, devices in standard UNIX terms. Metadevice names begin with the letter d. A metadevice is also called a submirror.