Administrator Guide

Table 43. Glossary of ME4 Series terms (continued)
Term Definition
CIMOM Common Information
Model Object Manager
A component in CIM that handles the interactions between management applications and
providers.
CNC Converged Network
Controller
A controller module whose host ports can be set to operate in FC or iSCSI mode, using
qualified SFP and cable options. Changing the host-port mode is also known as changing the
ports’ personality.
compatible disk A disk that can be used to replace a failed member disk of a disk group because it has at least
the same capacity as, and is of the same type (enterprise SAS, for example) as, the disk that
failed. See also available disk, dedicated spare, dynamic spare, global spare.
controller A (or B) A short way of referring to controller module A (or B). controller enclosure An enclosure that
contains one or two controller modules.
controller module A FRU that contains the following subsystems and devices: a Storage Controller processor;
a Management Controller processor; a SAS expander and Expander Controller processor;
management interfaces; cache protected by a supercapacitor pack and flash memory; host,
expansion, network, and service ports; and midplane connectivity.
CPLD Complex programmable logic device.
CQL CIM Query Language.
CRC Cyclic Redundancy Check.
CRU customer-replaceable
unit
A product module that can be ordered as a SKU and replaced in an enclosure by customers
or by qualified service personnel, without having to send the enclosure to a repair facility. See
also FRU.
CSV Comma-separated
values
A format to store tabular data in plain-text form.
DAS Direct Attached Storage A dedicated storage device that connects directly to a host without the use of a switch.
deallocation rate The rate, in pages per minute, at which a virtual pool is deallocating pages from its volumes
because they no longer need the space to store data.
dedicated spare A disk that is reserved for use by a specific linear disk group to replace a failed disk. See also
available disk, compatible disk, dynamic spare, global spare.
default mapping Host-access settings that apply to all initiators that are not explicitly mapped to that volume
using different settings. See also explicit mapping, masking.
DES Data Encryption Standard.
DHCP Dynamic Host Configuration Protocol. A network configuration protocol for hosts on IP
networks.
disk group A group of disks that is configured to use a specific RAID level and provides storage capacity
for a pool. See also linear disk group, virtual disk group, read cache.
drain The automatic movement of active volume data from a virtual disk group to other disk-group
members within the same pool.
drawer In a 5U84 enclosure, one of two FRUs that each holds 42 disks. drive enclosure See expansion
enclosure. See also EBOD, JBOD.
drive spin down See DSD.
DSD Drive spin down. A power-saving feature available for non-ADAPT linear disk groups that
monitors disk activity in the storage system and spins down inactive spinning disks based on
user-selectable policies. Drive spin down is not applicable to disks in virtual pools.
DSP Digital signal processor.
dual-port disk A disk that is connected to both controllers so it has two data paths, achieving fault tolerance.
Glossary of terms 183