Administrator Guide

Table 43. Glossary of ME4 Series terms (continued)
Term Definition
network port The Ethernet port on a controller module through which its Management Controller is connected to
the network.
NTP Network time protocol.
NV device Nonvolatile device. The CompactFlash memory card in a controller module. OID Object Identifier. In
SNMP, an identifier for an object in a MIB.
orphan data See unwritable cache data.
overcommit A setting that controls whether a virtual pool is allowed to have volumes whose total size exceeds the
physical capacity of the pool.
overcommitted The amount of storage capacity that is allocated to virtual volumes exceeds the physical capacity of
the storage system.
page A range of contiguous LBAs in a virtual disk group.
paged storage A method of mapping logical host requests to physical storage that maps the requests to virtualized
“pages” of storage that are in turn mapped to physical storage. This provides more flexibility for
expanding capacity and automatically moving data than the traditional, linear method in which
requests are directly mapped to storage devices. Paged storage is also called virtual storage.
parent volume A virtual volume that has snapshots (can be either a base volume or a base snapshot volume). The
parent of a snapshot is its immediate ancestor in the snapshot tree.
partner firmware update See PFU.
passphrase A user-created password that allows users to manage lock keys in an FDE-capable system. See also
FDE, lock key.
PCB Printed circuit board.
PCBA Printed circuit board assembly.
PCM Power and cooling module FRU. A power supply module that includes an integrated fan. See also
PSU.
PDU Power distribution unit. The rack power-distribution source to which a PCM or PSU connects. peer
connection The configurable entity defining a peer-to-peer relationship between two systems for the
purpose of establishing an asynchronous replication relationship. See also peer system.
peer system A remote storage system that can be accessed by the local system and is a candidate for
asynchronous replications. Both systems in a peer connection are considered peer systems to each
other, and they both maintain a peer connection with the other. Asynchronous replication of volumes
may occur in either direction between peer systems configured in a peer connection. See also peer
connection.
PFU Partner firmware update. The automatic update of the partner controller when the user updates
firmware on one controller.
PGR Persistent group reservations.
PHY One of two hardware components that form a physical link between devices in a SAS network that
enables transmission of data.
point-to-point Fibre Channel Point-to-Point topology in which two ports are directly connected. pool See linear pool,
virtual pool.
POST Power-on self test. Tests that run immediately after a device is powered on.
primary system The storage system that contains a replication set’s primary volume. See also replication set,
secondary system.
primary volume The volume that is the source of data in a replication set and that can be mapped to hosts. The
primary volume exists in a primary (linear storage) or pool (virtual storage) in the primary storage
system.
PSU Power supply unit
176 Glossary of terms