HP Netserver L Server series - Manual (Page 157)

Appendix B Glossary
151
Mirroring
Refers to the 100% duplication of data on one disk drive to another disk drive.
Each disk will be the mirror image of the other.
Pack
See "Drive Groups (or Drive Packs)."
Parity
See "Rotated XOR Redundancy."
Physical Drive States
Refers to a drive’s current operational status. At any given time, a drive can be in
one of four states: ONLINE, STANDBY, DEAD, or REBUILD.
The controller stores the state of the attached drives in its non-volatile memory.
This information is retained even after power-off. Hence, if a disk drive is labeled
DEAD in one session, it will stay in the DEAD state until a change is made either
by using a system level utility or after a rebuild. Each of the states is described
below:
Online: A disk drive is in an “online” state if it:
◊ Is powered on; and
◊ Has been defined as a member of a drive group; and
◊ Is operating properly.
Standby: A disk drive is in a “standby” state if it:
◊ Is powered on; and
◊ Is able to operate properly; and
◊ Was NOT defined as part of any drive group.
Dead: A disk drive is in a “dead” state if it:
◊ Is not present; or
◊ If it is present but not powered on; or
◊ If it failed to operate properly and was "killed" by the controller.
When the controller detects a failure on a disk, it "kills" that disk by
changing its state to "dead." A drive in a dead state does not participate
in any I/O activity. No commands are issued to dead drives.