Administrator Guide

Table 43. Glossary of ME4 Series terms (continued)
Term Definition
volume, and a LUN that identifies the volume to the host system. See also default mapping,
explicit mapping, masking.
masking A volume-mapping setting that specifies no access to that volume by hosts. See also default
mapping, explicit mapping.
MC Management Controller. A processor (located in a controller module) that is responsible
for human-computer interfaces, such as the PowerVault Manager, and computer-computer
interfaces, such as SNMP, and interacts with the Storage Controller. See also EC, SC.
metadata Data in the first sectors of a disk that stores disk-, disk-group-, and volume-specific
information including disk group membership or spare identification, disk group ownership,
volumes and snapshots in the disk group, host mapping of volumes, and results of the last
media scrub.
MIB Management Information Base. A database used for managing the entities in SNMP. midplane
The printed circuit board to which components connect in the middle of an enclosure. mount
To enable access to a volume from a host OS. See also host, map/mapping, volume.
midplane The printed circuit board to which components connect in the middle of an enclosure.
mount To enable access to a volume from a host OS. See also host, map/mapping, volume.
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
186 Glossary of terms