HP 3000 Enterprise Virtual Array - Manual (Page 150)

PDU Power Distribution Unit. The rack device that distributes conditioned AC or DC
power within a rack.
petabyte A unit of storage capacity that is the equivalent of 2 50 , 1,125,899,906,842,624
bytes or 1,024 terabytes.
physical disk A disk drive mounted in a drive enclosure that communicates with a controller
pair through the device-side Fibre Channel loops. A physical disk is hardware
with embedded software, as opposed to a virtual disk, which is constructed by
the controllers. Only the controllers can communicate directly with the physical
disks.
The physical disks, in aggregate, are called the array and constitute the storage
pool from which the controllers create virtual disks.
physical disk ar-
ray
See array .
port A Fibre Channel connector on a Fibre Channel device.
port_name A 64-bit unique identifier assigned to each Fibre Channel port. The port_name
is communicated during the login and port discovery processes.
port-wine colored A convention of applying the color of port wine to a CRU tab, lever, or handle
to identify the unit as hot-pluggable.
power distribution
module
See PDM .
power distribution
unit
See PDU .
power supply An element that develops DC voltages for operating the storage system elements
from either an AC or DC source.
preferred address An AL_PA which a node port attempts to acquire during loop initialization.
preferred path A preference for which controller of the controller pair manages the virtual disk.
This preference is set by the user when creating the virtual disk. A host can
change the preferred path of a virtual disk at any time. The primary purpose of
preferring a path is load balancing.
protocol The conventions or rules for the format and timing of messages sent and received.
push button A switch that is engaged or disengaged when it is pressed.
quiesce The act of rendering bus activity inactive or dormant. For example, “quiesce the
SCSI bus operations during a device warm-swap.”
rack A floorstanding structure primarily designed for, and capable of, holding and
supporting storage system equipment. All racks provide for the mounting of
panels per Electronic Industries Alliance (EIA) Standard RS310C.
rack-mounting
unit
A measurement for rack heights based upon a repeating hole pattern. It is
expressed as “U” spacing or panel heights. Repeating hole patterns are spaced
every 1.75 inches (44.45 mm) and based on EIA’s Standard RS310C. For
example, a 3U unit is 5.25inches (133.35 mm) high, and a 4U unit is 7.0inches
(177.79 mm) high.
read caching A cache method used to decrease subsystem response times to a read request
by allowing the controller to satisfy the request from the cache memory rather
than from the disk drives. Reading data from cache memory is faster than
reading data from a disk. The read cache is specified as either On or Off for
each virtual disk. The default state is on.
150 Glossary