Logical Units. Usually shortened to “units.” These are block devices presented to the operating system. A logical unit can be a one-tier, two-tier, or three-tier arrangement. Spare and Single logical units are examples of one-tier units. RAID 1 and RAID 5 are examples of two-tier units and as such will have sub-units. RAID 10 and RAID 50 are examples of three-tier units and as such will have sub-sub-units.
Port. 3ware controller models up to the 9650SE series have one or many ports (typically 4, 8, 12, 16, or 24). Each port can be attached to a single disk drive. On a controller such as the 9650SE with a multilane serial port connector, one connector supports four ports. On 9690SA series controllers, connections are made with phys and vports (virtual port).
Phy. Phys are transceivers that transmit and receive the serial data stream that flows between the controller and the drives. 3ware 9690SA controllers have 8 phys. These “controller phys” are associated with virtual ports (vports) by 3ware software to establish up to 128 potential connections with SAS or SATA hard drives. Each controller phy can be connected directly to a single drive, or can be connected through an expander to additional drives.
VPort. Connections from 3ware 9690SA controllers to SAS or SATA drives are referred to as
virtual ports, or VPorts. A VPort indicates the ID of a drive, whether it is directly connected to the controller, or cascaded through one or more expanders. The VPort, in essence, is a handle in the software to uniquely identify a drive. The VPort ID or port ID allows a drive to be consistently identified, used in a RAID unit, and managed. For dual-ported drives, although there are two connections to a drive the drive is still identified with one VPort handle.