Owner's manual

data entry mode The state in which controller information can be displayed or controller
configuration data can be entered. On the Enterprise Storage System, the
controller mode is active when the LCD on the HSV Controller OCP is Flashing.
default disk g roup The first disk group created at the time the system in initialize d. The default
disk group can contain the entire set of physical d isks in the array or just a
few of the disks.
See also disk group.
Detailed Fault
View
An HSV Controller OCP display that permits a user to view detailed information
about a controller fault.
device channel A channel used to connect storage devices to a host I/O bus adapter or
intelligent controller.
device ports Controller pair device ports connected to the storage system’s physical disk drive
array through the Fibre Channel d rive enclosure. Also ca lled a device-side port.
device-side ports See device ports.
DIMM Dual Inline Memory Module. A small circuit board holding memory chips.
dirty data The write-back cached data that has not been written to storage media even
though the host operation processing the data has completed.
disk drive A carrier-mounted storage device supporting random access to fixed size blocks
of data.
disk drive blank A carrier that replaces a disk drive to control airflow within a drive enclosure
whenever there is less than a full complement of storage devices.
drive enclosure A unit that holds storage system devices such as disk drives, power supplies,
blowers, I/O modu les, transceivers, or EMUs.
drive enclosure
event
Asignificant operational occurrence involving a hardware or software
component in the drive enclosure. The drive enclosure EMU reports these events
to the controller for processing.
disk failure pro-
tection
A m ethod by which a controller pair reserves drive capacity to take over the
functionality of a failed or failing physical disk. For e ach disk group, the
controllers reserve space in the p hysical disk pool equivalent to the selected
number of physical disk drives.
disk group A physical disk drive set or pool in which a virtual disk is created. A disk group
may c ontain a ll the physical disk drives in a controller p air array or a subset
of the array.
disk migration
state
A physical disk drive operating state. A physical disk drive can b e in a stable
or migration state:
• Stable—The state in which the physical disk drive has no failure nor is a
failure predicted.
• Migration—The state in which the disk drive is failing, or failure is predicted
to be imminent. Data is then moved off the disk onto other disk drives in
thesamediskgroup.
disk replacement
delay
The time that elapses between a drive failure and when the controller starts
searching for spare disk space. Driv e replacement se
ldom star ts immediately in
case the “failure” was a glitch or temporary c onditi
on.
drive blank See disk drive blank.
drive enclosure See drive enclosure.
dual-loop Aconfiguration where each drive is connected to a pair of controllers through
two loops. These t wo Fibre Channel loops constitute a loop pair.
150
Glossary