HP-UX System Administrator's Guide: Overview HP-UX 11i v3 (B3921-90011, September 2010)

Device file types:
• Legacy Device Special Files — the traditional, hardware path dependent style of device
special file. Each path to a device has its own device special file. Moving a device means
using different device special files to access the device.
• Persistent device special files — the newer, hardware path independent style of device special
files. Because of the hardware path independence, moving a device to a different hardware
path does not require you to use a new device special file, or even change the current one.
Device file access:
• Block Special Files – Device files associated with block devices. Block devices transfer data
in multi-byte blocks by means of the system's normal buffering mechanism.
• Character Special Files – Device files associated with character-mode devices, such as printers,
most terminals, and modems. Character-mode devices transfer data in an unbuffered
stream.
device swap Swap space located in a dedicated disk volume or disk partition. Device swap is not part of a
file system and is not memory based. Device swap is generally faster than file system swap
because it is more direct (does not have the file system layer to traverse).
See also file system swap, and pseudo swap.
directory path A string of characters representing the sequence of directories that must be traversed from the
root directory (“/”) to the directory represented by the path. Directory names in the path string
are delimited by the slash character (“/”).
Example: /usr/share/man/man1.Z/cat.1
disable
One of four commands that control the flow of print requests through the Line Printer Spooling
System (spooler). disable instructs the spooler to prevent queued requests from flowing out
of a print queue; in other words, to prevent the printing of requests from a queue.
See also accept, reject, enable.
disk group (1) A VxVM disk group is conceptually similar to an LVM volume group. It is a collection of
VM disks that share a common configuration.
(2) A collection of individual disks that share a common role in disk array operation. All disks
on the disk array will be a member of one of the following disk groups: a LUN, hot spare, or
unassigned.
disk striping A method of writing to a logical disk device (for example, an LVM logical volume or VxVM
Volume) comprised of multiple physical devices such that consecutive chunks of data (such as
bits, bytes, or blocks, or extents) are distributed to different physical devices. This can speed
up logical device access as multiple data chunks can be written or read simultaneously to or
from the different physical devices.
dump
concurrency
The ability to dump to multiple devices in parallel, speeding up memory dumps and shortening
system downtime.
Dynamic Root
Disk (DRD)
An HP-UX based tool set that enables you to create and modify an inactive system image (a
clone of your running system), on a separate disk, without having to shut down the system.
Once created, the cloned system image can be used for system recovery, can be updated offline
to a newer version of HP-UX to be booted at a more convenient time, or it can be used to boot
another system (real or virtual).
enable
One of four commands that control the flow of print requests through the Line Printer Spooling
System (spooler). enable instructs the spooler to allow queued requests to flow out of a print
queue; in other words, to actually be printed.
See also accept, reject, disable.
event An indication, provided by any system component or application that something noteworthy
has occurred. Events are made available to any interested entity by being posted to the Event
Manager subsystem.
See also Event Manager (EVM).
Event
Management
Daemon
Part of the Event Manager subsystem, the event management daemon (/usr/sbin/evmd)
provides posting and notification services for system and application clients running on the
local system.
See also Event Manager (EVM) and the evmd1M manpage.
110 Glossary