McDATA Eclipse 2640 SAN, Administration And Configuration Manual

Page: 218 / 276

g-8 Eclipse™ 2640 SAN Router Administration and Configuration Manual
Glossary
write-back caching is enabled, this RAM can contain data that is not
yet written to the disks in the array. In normal circumstances, this
data is flushed from the RAM to the disk drives in the array with a
maximum latency of 64 ms. If power fails to the subsystem
(preventing the data from being written to the disk drives in the
array), the battery holds the data for approximately 72 hours. If
power is restored within that period, the data is flushed into the array
and operation continues normally. If power has not been restored
within 72 hours the data is lost.
cache memory
A memory subsystem that stores recently used instructions and data
for fast access. The larger the cache, the more information that can be
stored, and the fewer time-consuming memory accesses a central
processing unit (CPU) must make to complete a task. Cache is very
fast memory, typically static random access memory (SRAM).
capacity
The amount of information, measured in bytes, that can be stored on
a hard drive.
cascade
Linking two or more FC switches to form a larger switch or fabric.
The switched link through fiber cables attached between one or more
expansion ports (E_Ports).
See also
expansion port .
central processing
unit
CPU. The heart of the computer, this is the component that actually
executes instructions.
central processor
complex
CPC. A physical grouping of hardware that includes a main storage
device, one or more central processors, timers, and channels.
chained
Two directors or switches that are physically attached.
one or two channels (primary and secondary). If a motherboard has
only one channel, it may be necessary to add a controller card to
create a secondary channel.
channel-attached
(1) Pertaining to direct attachment of devices by data I/O channels to
a computer
(D)
. (2) Pertaining to devices attached to a control unit by
cables, not telecommunication lines
(D)
.
Synonymous with
local .
Class 2 Fibre Channel
service
Provides a connectionless (not dedicated) service with notification of
delivery or nondelivery between two node ports (N_Ports).
Class 3 Fibre Channel
service
Provides a connectionless (not dedicated) service without notification
of delivery or nondelivery between two node ports (N_Ports).
Synonymous with
datagram .