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ISR651101-00 J Glossary-7
Installation Guide QLogic intelligent Storage Router (iSR)
6200 Series
OC
Optical carrier is a standardized set of
specifications of transmission speeds that
describe a range of digital signals that can
be carried on synchronous optical
networking (SONET) fiber optic networks.
The number attached to the optical carrier
abbreviation, OC-12, is directly propor-
tional to the data rate of the bitstream of
the digital signal.
path
A path to a device is a combination of a
adapter port instance and a target port as
distinct from internal paths in the fabric
network. A fabric network appears to the
operating system as an opaque network
between the adapter (initiator) and the
target.
Because a path is a combination of an
adapter and a target port, it is distinct from
another path if it is accessed through a
different adapter and/or it is accessing a
different target port. Consequently, when
switching from one path to another, the
driver might be selecting a different
adapter (initiator), a different target port, or
both.
This is important to the driver when
selecting the proper method of failover
notification. It can make a difference to the
target device, which might have to take
different actions when receiving retries of
the request from another initiator or on a
different port.
PCI
Peripheral component interface/intercon-
nect. A 32-bit local bus specification intro-
duced by Intel.
PCM
Power and cooling module. A device that
consists of one power supply and three
fans.
PID
Process identifier. A number used by some
operating system kernels (such as that of
UNIX, Mac OS X or Windows NT) to
uniquely identify a process.
ping
A computer network administration utility
used to test whether a specified host is
reachable across an IP network and to
measure the round-trip time for packets
sent from the local host to a destination
computer.
point-to-point
Also FC-P2P. Two Fibre Channel nodes
directly connected (not in a loop).
port
Access points in a device where a link
attaches. There are four types of ports, as
follows:
N_Port—a Fibre Channel port that
supports point-to-point topology.
NL_Port—a Fibre Channel port that
supports loop topology.
Fibre Channel—a port in a fabric
where an N_Port can attach.
Fibre Channel—a port in a fabric
where an NL_Port can attach.
port instance
The number of the port in the system.
Each adapter may have one or multiple
ports, identified with regard to the adapter
as port 0, port 1 and so forth. To avoid
confusion when dealing with a system
containing numerous ports, each port is
assigned a port instance number when the
system boots up. So Port 0 on an adapter
might have a port instance number of 8, for
example, if it is the eighth port discovered
by the system.