Avago Technologies 3ware SAS 9750-4i - Manual (Page 30)

Chapter 2. CLI Syntax Reference
22 3ware SATA+SAS RAID Controller Card CLI Guide, Version 10.0
Terminology
3ware SATA+SAS RAID Controller Card CLI Guide, Version 10.0 uses the
following terminology:
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 9750 and 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 9750 and 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 9750 and 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.
For additional information about 3ware controller concepts and terminology,
see the user guide PDF for your 3ware RAID controller or the user guide
portions of the 3ware HTML Bookshelf.
Note: For practical purposes, port and VPort are used interchangeably in this
document in reference to a drive (or disk). Therefore, unless otherwise specified,
the mention of port implies VPort as well. For example, when “port” is used to
indicate a drive, it is implied that for the applicable controller series, the reference
also applies to VPort.