Avago Technologies MegaRAID SAS 9240-4i - Manual (Page 90)

LSI Corporation
- 90 -
6Gb/s MegaRAID SAS RAID Controllers User Guide
August 2013
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
NVRAM Acronym for nonvolatile 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 (PCIe) 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.