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96257 Sun Confidential: Internal Only C-87
Revision A
CD-ROM. Compact Disc Read-Only Memory. An optical
disc that may contain computer data, audio data, graph-
ics, and other information, and is interchangeable be-
tween different types of computers. Storage capacity is
typically about 680 MB per disc.
CDS. Control data set. An HSC database containing all
configuration and volume information, used by host soft-
ware to control functions of automated libraries.
CEI. Configured end item.
CFE. Composite Failure Event. In VTSS, a structure
formed for each discrete failure domain.
CFT. Controlled field test.
change journal. In VSM, the record of changes to the
functional track directory (FTD) that is kept in nonvolatile
storage (NVS) and is then written to the disk arrays
(VTSS). VSM uses the change journal to reconstruct the
FTD in the event of a failure.
channel. (1) A point-to-point link whose primary task is
to transport data from one point to another. (2) A path for
transfer of data and control information between a disk
drive and array controller. (3) A device that connects a
host and main storage with the I/O control units.
channel image. A software image that logically presents
itself as a single physical channel, regardless of how the
physical connection is made. Each channel image ap-
pears to be an independent single physical channel, al-
though all channel images on a specific I/O interface
share the same facilities and physical paths. A VSM5-
VTSS presents up to 16 control unit images to each of 1
to 28 host systems.
channel interface. Controller circuitry that attaches host
channels.
check0. An error condition detected within a VTSS pro-
cessor card that affects the integrity of the processor. If a
second check 0 is detected within the same processor
during recovery, the processor hard-stops (a ‘double
check 0’ condition), making the operation or condition
unrecoverable by the failing processor.
check1. An error condition that affects a control bus or
shared memory bus but leaves processor cards function-
al. Check1 may affect all processors on a bus, since the
bus is locked until the condition is cleared.
check2. An error condition detected in the non-proces-
sor logic cards.
checksum. A value that accompanies data transferred
between points to ensure the data is transferred correct-
ly. Checksum is computed by adding up the bytes or
words of a data block. On the receiving end, checksum is
computed based on the data received and compared
with the value that was sent with the data. If the two
numbers match, the data is considered to be correct.
CHPID. Channel-path identifier. A value assigned to an
installed channel path that provides for its discrete recog-
nition by a VTSS.
circuit breaker. A switch that automatically interrupts an
electrical circuit when there is an overload of current or
other abnormal condition.
CKD. See count-key data
.
client. A system which is able to operate independently
but has some degree of dependence on another system.
Frequently refers to computers on a LAN. A client is a re-
cipient of services in a client/server application. Clients
can be workstations, PCs, or other servers.
client/server. A system architecture in which one or
more programs (clients) request computing or data ser-
vices, such as data storage, processing, or transmission,
from another program (server).
clink. clustered link. An ESCON port used to link a mas-
ter and slave VTSS in a clustered configuration.
clock speed. In storage systems, the frequency at which
the system clock oscillates, as measured in MHz. The
faster the clock, the more quickly the system can trans-
mit information.
clustering. (1) In VSM, the process of writing a virtual
tape volume (VTV) onto two discrete VTSSs. (2) A tech-
nique for configuring two or more servers as a single pro-
cessing system using software and hardware to allow
sharing of storage, processing, and other resources un-
der a single management domain, thereby providing
greater data accessibility and higher reliability.
CM. Configuration Management. (1) Identification and
management of physical product configurations through
documentation, records, and data. (2) An organization
within Sun responsible for applying these disciplines
through a formal EC process.
cold boot. The act of switching a computer, storage sys-
tem, etc. Completely off, then switching it back on again.
Contrast with warm boot
.
cold swap. To remove and replace a system component
(typically one such as a logic board that has no redun-
dant backup) after system operations have been stopped
and power has been disabled. Contrast with hot swap
.
collected free space. Array cylinders that are collected
and completely free of user data.
collocation. A process that attempts to keep all data be-
longing to a single client node on a minimal number of
sequential-access media volumes within a storage pool.
Used to minimize the number of volumes that must be
accessed when a large amount of data must be restored.
command line interface. A user interface in which com-
mands are keyed onto a command line instead of
through a Graphical User Interface. Contrast with GUI
.
compaction. The elimination of inter-record gaps nor-
mally associated with count-key data DASD that allows
less disk storage space to be used, reducing net capaci-
ty load in VTSS units.
compression. The process of encoding data using algo-
rithms so that it uses less storage space and/or increas-
es the rate, or speed, of data transmission.
Configuration Control Document (CCD). A Sun docu-
ment which defines model numbers, family ID codes,
feature codes, part numbers, etc. for a specific product,
and which identifies the configured end items (CEIs)
available for use in the product.
Configuration Status Monitor (CSM). In VTSS, a part
of the Failure Management System (FMS) that monitors
FRU configurations in the controller, performs FRU vali-
dation, and coordinates diagnostic fencing.
controlled power-down (CPD). An orderly sequence of
steps that shuts off AC power to a system without jeopar-
dizing customer data.
controller. A system control module or storage control
unit. Also called a control module
or control unit. See al-
so disk array controller.
control region. VTSS data path control. Hardware in a
multipath controller that is associated with a data path
and which transfers data between the cache and disk ar-
rays and between cache and host channel(s).