IBM SAN16B-2 - TotalStorage Express Model Switch User And Service Manual page 80

primitive signal. A part of an ordered set that
indicates events. See also ordered set.
principal switch. The switch that assumes the
responsibility to assign domain IDs. The role of principal
switch is negotiated after a "build fabric" event.
private device. A device that supports arbitrated loop
protocol and can interpret 8–bit addresses, but cannot
log into the fabric.
private loop. An arbitrated loop that does not include
a participating fabric loop port (FL_port).
private key. The secret half of a key pair.
private loop direct attach (PLDA). A subset of fibre
channel standards for the operation of peripheral
devices.
private NL_port. A node loop port (NL_port) that
communicates only with other private NL_ports in the
same loop and does not log into the fabric.
protocol. A defined method and a set of standards for
communication.
public device. A device that supports arbitrated loop
protocol, can interpret 8–bit addresses, and can log into
the fabric.
public loop. An arbitrated loop that includes a
participating fabric loop port (FL_port), and can contain
both public and private node loop ports (NL_ports).
public NL_port. A node loop port (NL_port) that logs
into the fabric, can function within either a public or
private loop, and can communicate with either private or
public NL_ports.
Q
quad. A group of four adjacent ports that share a
common pool of frame buffers.
QuickLoop. (1) A software feature that makes it
possible to allow private devices within loops to
communicate with public and private devices across the
fabric through the creation of a larger loop. (2) The
arbitrated loop created using this software. A QuickLoop
can contain a number of devices or looplets; all devices
in the same QuickLoop share a single arbitrated loop
physical address (AL_PA) space.
QuickLoop mode. A hardware translative mode that
allows private devices to communicate with other private
devices across the fabric. See also hardware translative
mode and standard translative mode.
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SAN16B-2 Installation, Service, and User's Guide
R
RAID. See redundant array of independent disks.
RAM. See random access memory.
random access memory (RAM). A temporary storage
location in which the central processing unit (CPU)
stores and executes its processes.
R_A_TOV. See resource allocation timeout value.
read only memory (ROM). Memory in which stored
data cannot be changed by the user except under
special conditions.
receiver ready (R_RDY). A primitive signal indicating
that the port is ready to receive a frame.
redundant array of independent disks (RAID). A
collection of disk drives that appear as a single volume
to the server and are fault tolerant through mirroring or
parity checking.
registered state change notification (RSCN). A
switch function that allows notification of fabric changes
to be sent from the switch to specified nodes.
remote fabric. A fabric that spans across wide area
networks (WANs) by using protocol translation (a
process also known as tunneling) such as fibre channel
over asynchronous transfer mode (ATM) or fibre
channel over Internet protocol (IP).
remote switch. A optional feature for long distance
fabrics, requireing a Fibre Channel to ATM or SONET
gateway.
request rate. The rate at which requests arrive at a
servicing entity. See also service rate.
resilience. A fabric's ability to adapt to or tolerate a
failure of a component within the fabric.
resilient core. A single fabric that uses two or more
switches as a core to interconnect multiple edge
switches. Synonymous with dual-core fabric.
resource allocation timeout value (R_A_TOV). Used
to time out operations that depend on the maximum
possible time that a frame can be delayed in a fabric
and still be delivered. This value is adjustable in one
microsecond increments from 10—120 seconds.
resource recover timeout value (RR_TOV). The
minimum time a target device in a loop waits after a
loop initialization primitive (LIP) before logging out a
small computer systems interface (SCSI) initiator. See
also error detect timeout value and resource allocation
timeout value.
RLS probing. Read link status of the arbitrated loop
physical addresses (AL_PAs).