Avago Technologies Cache Protection for RAID Controller Cards - Manual (Page 41)

LSI Corporation
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12Gb/s MegaRAID SAS RAID Controllers User Guide
April 2014
Glossary
I
internal SAS device
A SAS device installed inside the computer cabinet. These devices are connected by using a shielded cable.
M
main memory
The part of computer memory that is directly accessible by the CPU (usually synonymous with RAM).
N
NVSRAM
Acronym for nonvolatile static random access memory. An EEPROM (electronically erasable read-only memory) chip that stores
configuration information. See
EEPROM .
P
PCI
Acronym for peripheral component interconnect. A high-performance, local bus specification that allows the connection of devices
directly to computer memory. The PCI Local Bus allows transparent upgrades from 32-bit data path at 33 MHz to 64-bit data path at
33 MHz, and from 32-bit data path at 66 MHz to 64-bit data path at 66 MHz.
PCI Express
Acronym for peripheral component interconnect Express. A high-performance, local bus specification that permits the connection
of devices directly to computer memory. PCI Express is a two-way, serial connection that transfers data on two pairs of point-to-
point data lines. PCI Express goes beyond the PCI specification in that it is intended as a unifying I/O architecture for various
systems: desktops, workstations, mobile, server, communications, and embedded devices.
peripheral devices
A piece of hardware (such as a video monitor, drive, printer, or CD-ROM) used with a computer and under the control of the
computer. SCSI peripherals are controlled through a MegaRAID SAS RAID controller (host adapter).
PHY
The interface required to transmit and receive data packets transferred across the serial bus.
Each PHY can form one side of the physical link in a connection with a PHY on a different SATA device. The physical link contains
four wires that form two differential signal pairs. One differential pair transmits signals, while the other differential pair receives
signals. Both differential pairs operate simultaneously and allow concurrent data transmission in both the receive and the
transmit directions.
R
RAID
Acronym for Redundant Array of Independent Disks (originally Redundant Array of Inexpensive Disks). An array (group) of multiple
independent drives managed together to yield higher reliability, performance, or both exceeding that of a single drive. The RAID
array appears to the controller as a single storage unit. I/O is expedited because several drives can be accessed simultaneously.
Redundant RAID levels (RAID levels 1, 5, 6, 10, 50, and 60) provide data protection.
RAID levels
A set of techniques applied to drive groups to deliver higher data availability, performance characteristics, or both to host
environments. Each virtual drive must have a RAID level assigned to it.
S
SAS
Acronym for Serial Attached SCSI. A serial, point-to-point, enterprise-level device interface that leverages the proven SCSI protocol
set. The SAS interface provides improved performance, simplified cabling, smaller connections, lower pin count, and lower power
requirements when compared to parallel SCSI. SAS controllers leverage a common electrical and physical connection interface that
is compatible with Serial ATA.
The SAS controllers support the ANSI Serial Attached SCSI Standard, Version 2.0. In addition, the controller supports the Serial
ATA III (SATA III) protocol defined by the Serial ATA Specification, Version 3.0. Supporting both the SAS interface and the SATA III
interface, the SAS controller is a versatile controller that provides the backbone of both server and high-end workstation
environments. Each port on the SAS RAID controller supports SAS devices, SATA devices, or both.