Hitachi Copy-on Write SnapShot, User Manual

Page: 74 / 90

Glossary–2
Hitachi Simple Modular Storage Copy-on-Write SnapShot User’s Guide
•
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
array
A set of hard disks mounted in a single enclosure and grouped logically
together to function as one contiguous storage space.
asynchronous
Asynchronous data communications operate between a computer and
various devices. Data transfers occur intermittently rather than in a
steady stream. Asynchronous replication does not depend on
acknowledging the remote write, but it does write to a local log file.
Synchronous replication depends on receiving an acknowledgement
code (ACK) from the remote system and the remote system also keeps
a log file.
B
background copy
A physical copy of all tracks from the source volume to the target
volume.
bps
Bits per second, the standard measure of data transmission speeds.
C
cache
A temporary, high-speed storage mechanism. It is a reserved section of
main memory or an independent high-speed storage device. Two types
of caching are found in computers: memory caching and disk caching.
Memory caches are built into the architecture of microprocessors and
often computers have external cache memory. Disk caching works like
memory caching; however, it uses slower, conventional main memory
that on some devices is called a memory buffer.
capacity
The amount of information (usually expressed in megabytes) that can
be stored on a disk drive. It is the measure of the potential contents of
a device; the volume it can contain or hold. In communications,
capacity refers to the maximum possible data transfer rate of a
communications channel under ideal conditions.
CCI
See command control interface.