HP 3000 Enterprise Virtual Array - Manual (Page 211)

Glossary
211 Enterprise Virtual Array 3000 User Guide
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.
disk drive enclosure
A unit that holds storage system devices such as disk drives, power supplies, blowers, I/O
modules, transceivers or EMUs.
disk drive enclosure event
A significant operational occurrence involving a hardware or software component in the disk
drive enclosure. The disk drive enclosure EMU reports these events to the controller for
processing.
disk failure protection
A method by which a controller pair reserves drive capacity to take over the functionality of a
failed or failing physical disk. For each disk group, the controllers reserve space in the
physical 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 contain
all the physical disk drives in a controller pair array or a subset of the array.
disk migration state
A physical disk drive operating state. A physical disk drive can be 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 the same disk group.