Administrator Guide

Table Of Contents
Table 43. Glossary of ME4 Series terms (continued)
Term Definition
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.
EMP Enclosure management processor. An Expander Controller subsystem that provides SES data
such as temperature, power supply and fan status, and the presence or absence of disks.
enclosure A physical storage device that contains I/O modules, disk drives, and other FRUs. See also
controller enclosure, expansion enclosure.
enclosure management
processor
See EMP.
ESD Electrostatic discharge.
ESM Environmental Service Module. See IOM.
Expander Controller See EC.
expansion enclosure An enclosure that contains one or two expansion modules. Expansion enclosures can be
connected to a controller enclosure to provide additional storage capacity. See also EBOD,
JBOD.
expansion module A FRU that contains the following subsystems and devices: a SAS expander and Expander
Controller processor; host, expansion, and service ports; and midplane connectivity.
explicit mapping Access settings for an initiator to a volume that override the volumes default mapping. See
also default mapping, masking.
failback See recovery.
failover In an active-active configuration, failover is the act of temporarily transferring ownership
of controller resources from an offline controller to its partner controller, which remains
operational. The resources include pools, volumes, cache data, host ID information, and LUNs
and WWNs. See also recovery.
fan module The fan FRU used in 5U84 enclosures. There are five in each enclosure, separate from the
PSUs. FC Fibre Channel.
FC-AL Fibre Channel Arbitrated Loop. The FC topology in which devices are connected in a one-way
loop.
FDE Full Disk Encryption. A feature that secures all the user data on a storage system. See also
lock key, passphrase, repurpose, SED.
FPGA Field-programmable gate array. An integrated circuit designed to be configured after
manufacturing.
FRU field-replaceable unit. A product module that can be replaced in an enclosure by qualified
service personnel only, without having to send the enclosure to a repair facility. Product
interfaces use the term FRU to refer to both FRUs and CRUs. See CRU.
Full Disk Encryption See FDE.
GEM Generic Enclosure Management. The firmware responsible for managing enclosure electronics
and environmental parameters. GEM is used by the Expander Controller.
global spare A compatible disk that is reserved for use by any disk group with a fault-tolerant RAID level to
replace a failed disk. See also available disk, compatible disk, dedicated spare, dynamic spare.
184 Glossary of terms