Administrator Guide

Table 43. Glossary of ME4 Series terms (continued)
Term Definition
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 volume’s 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.
HBA Host bus adapter. A device that facilitates I/O processing and physical connectivity between a host
and the storage system.
host A user-defined group of initiators that represents a server.
host group A user-defined group of hosts for ease of management, such as for mapping operations. host port A
port on a controller module that interfaces to a host computer, either directly or through a network
switch.
initiator An external port to which the storage system is connected. The external port may be a port in an I/O
adapter in a server, or a port in a network switch.
I/O Manager An SNMP MIB term for a controller module.
I/O module See IOM
IOM Input/output module, or I/O module. An IOM can be either a controller module or an expansion
module.
174 Glossary of terms