3Ware 9550SXU-12 User Guide - Page 330

Glossary 318 • OCE (Online Capacity Expansion). The process of increasing the size of an existing RAID unit without having to create a new unit. See also migration. • Parity. Information that the controller calculates using an exclusive OR (XOR) algorithm and writes to the disk drives in RAID 5, RAID 6, and RAID 50 units. This data can be used with the remaining user data to recover the lost data if a disk drive fails. • PCB. Printed circuit board. • P-Chip. PCI interface chip that connects the PCI bus to the high-speed internal bus and routes all data between the two using a packet switched fabric. There is one P-chip per controller card. • 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 phys are associated with virtual ports (vports) by 3ware software to establish up to 128 potential connections with the SAS or SATA hard drives. • Phy Identifier. The ID number (0-7) assigned to each of the 8 phys on the 9690SA controller. • Port. 3ware controller models prior to the 9690SA 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 with a Multi-lane™ serial port connector, one connector supports four ports (eight if 24-port controller). On 9690SA series controllers, connections are made with phys and vports (virtual ports). See "phy" and "VPort". • Port ID. A unique identifier for a specific port in a system. Also called a drive ID. • Queuing. SATA drives can use Native Command Queuing (NCQ) to improve performance in applications that require a lot of random access to data, such as server-type applications. When NCQ is enabled, the commands are reordered on the drive itself. NCQ must be supported by the drive. NCQ must be turned on in both the drive and the RAID controller. By default, the RAID unit's queue policy is disabled when creating a unit. • RAID. Redundant array of inexpensive disks, combined into a unit (array), to increase your storage system's performance and provide fault tolerance (protection against data loss). • Rapid RAID Recovery. The Rapid Raid Recovery feature increases the speed with which a redundant unit can be made redundant again when a rebuild is required. It can also increase the speed of verification or initialization that may occur in the event of an unclean shutdown. 3ware SAS/SATA RAID Software User Guide, Version 9.5.1