HP MSA 2040 SAN Storage - Manual (Page 29)

Glossary 29
Glossary
chunk size The amount of contiguous data that is written to a vdisk member before moving to the next
member of the vdisk.
compatible disk A disk that has enough capacity to replace a failed disk and is the same type (SAS or
SATA).
dedicated spare A disk that is reserved for use by a specific vdisk to replace a failed disk. See compatible
disk.
default mapping Host-access settings that are configured when a volume is created, and that apply to all
hosts that are not explicitly mapped to that volume using different settings. See also explicit
mapping and masking.
drive spin down (DSD) A power-saving feature that monitors disk activity in the storage system and spins down
inactive SAS and SATA disks, based on user-selectable policies.
dual-port disk A disk that is connected to both controllers so its data path is fault-tolerant.
dynamic spare An available compatible disk that is automatically assigned, if the dynamic spares option is
enabled, to replace a failed disk in a redundant vdisk. See compatible disk.
EC Expander Controller. The 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.
EMP Enclosure management processor. An EC subsystem that provides SES data such as
temperature, power supply and fan status, and the presence or absence of disks.
explicit mapping Access settings for a host to a volume that override the volume’s default mapping. See also
default mapping and masking.
FC Fibre Channel interface protocol.
global spare A disk that is reserved for use by any redundant vdisk to replace a failed disk. See
compatible disk.
host An external port that the storage system is attached to. The external port may be a port in
an I/O adapter in a server, or a port in a network switch.
image ID A globally unique serial number that identifies the point-in-time image source for a volume.
All volumes that have identical image IDs have identical data content, whether they be
snapshots or stand-alone volumes.
leftover The state of a disk that has been automatically excluded from a vdisk, and is no longer
needed by the vdisk after the vdisk is reconstructed.
loop Fibre Channel Arbitrated Loop (FC-AL) topology.
masking Volume-mapping settings that specify no access to that volume by hosts. See also default
mapping and explicit mapping.
master volume A volume that is enabled for snapshots and has an associated snap pool.
MC Management Controller. The processor (located in a controller module) that is responsible
for human-computer interface and computer-computer interface functions, and interacts with
the SC.
metadata Data in the first sectors of a disk drive that stores all disk, vdisk, and volume specific
information including vdisk membership or spare identification, vdisk ownership, volumes
and snapshots in the vdisk, host mapping of volumes, and results of the last media scrub.
network port The Ethernet port on a controller module through which its Management Controller is
connected to the network.
point-to-point Fibre Channel Point-to-Point topology.