Administrator Guide

Table 43. Glossary of ME4 Series terms (continued)
Term Definition
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.
dynamic spare An available compatible disk that is automatically assigned, if the dynamic spares option
is enabled, to replace a failed disk in a disk group with a fault-tolerant RAID level. See also available
disk, compatible disk, dedicated spare, global spare.
EBOD Expanded Bunch of Disks. Expansion enclosure attached to a controller enclosure.
EC Expander Controller. A processor (located in the SAS expander in each controller module and
expansion module) that controls the SAS expander and provides SES functionality. See also EMP.
EEPROM Electrically erasable programmable ROM.
Glossary of terms 173