IBM DS8000 User Manual page 233

planar The main printed circuit board (PCB) that
other PCBs or assemblies plug into. The
planar distributes both power and signals
and therefore creates a common
communications path to whichever device
that plugs into it.
point-in-time copy
A FlashCopy option that creates an
instantaneous view of original source data
at a specific moment in time.
point-to-point connection
A fibre-channel topology that enables the
direct interconnection of ports. See also
arbitrated loop and switched fabric.
port A physical connection on a host adapter
to the cable that connects the DS8000 to
hosts, switches, or another DS8000. The
DS8000 uses SCSI and ESCON host
adapters that have two ports per adapter,
and fibre-channel host adapters that have
one port. See also ESCON, fibre-channel,
host adapter, and small computer system
interface.
POST See power-on self test.
power-on self test (POST)
A diagnostic test that servers or
computers run when they are turned on.
predictable write
A write operation that can cache without
knowledge of the existing format on the
medium. All write operations on FBA
DASD devices are predictable. On CKD
DASD devices, a write operation is
predictable if it does a format write
operation for the first data record on the
track.
primary control unit
The DS8000 to which a Remote Mirror
and Copy primary device is physically
attached.
processor complex
A partition of a storage server that is
capable of performing all defined
functions of the storage server. Multiple
processor complexes provide redundancy.
product engineering
See IBM product engineering.
program
On a computer, a generic term for
software that controls the operation of the
computer. Typically, the program is a
logical assemblage of software modules
that perform multiple related tasks.
program-controlled interruption
An interruption that occurs when an I/O
channel fetches a channel command word
with the program-controlled interruption
flag on.
program temporary fix (PTF)
A temporary solution to, or bypass of, a
problem diagnosed by IBM as the result
of a defect in a current unaltered release
of a licensed program. (GC)
promote
To add a logical data unit to cache
memory.
protected volume
In AS/400, a disk storage device that is
protected from data loss by RAID
techniques. An AS/400 host does not
mirror a volume configured as a protected
volume, while it does mirror all volumes
configured as unprotected volumes. The
DS8000, however, can be configured to
indicate that an AS/400 volume is
protected or unprotected and give it
RAID protection in either case.
protocol data unit (PDU)
A unit of data specified in the protocol of
a given layer and consisting of protocol
control information for the layer and,
possibly, user data for the layer.
pseudo host
A host connection that is not explicitly
defined to the DS8000 and that has access
to at least one volume that is configured
on the DS8000. The FiconNet pseudo host
icon represents the FICON protocol. The
EsconNet pseudo host icon represents the
ESCON protocol. The pseudo host icon
labelled Anonymous represents hosts
connected through the FCP protocol.
Anonymous host is a commonly used
synonym for pseudo host. The DS8000
adds a pseudo host icon only when it is
set to access-any mode. See also access-any
mode.
PTF See program temporary fix.
PV Links
Short for Physical Volume Links, an
alternate pathing solution from
205
Glossary