HP Surestore 6.140 Tape Library - Manual (Page 195)

Appendix C C-11
Introduction to Fibre Channel
Fibre Channel Technology
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Zoning
Zoning is a management method used to control which ports on a hub, or
switch, can communicate with each other. Zoned operations are
controlled by system administrators and host computer applications. The
HP SureStore Tape Library functions the same on zoned and non-zoned
systems.
With a hub, zoning divides a larger loop into multiple smaller,
independent loops. With a switch, zoning limits which ports can be
accessed. Reasons a system administrator, or an application program,
would want to limit access include providing security for computer
systems, and restricting computer systems access to disk drives with
sensitive data.
Zoning also allows different computer systems to coexist on the same
network. For example, NT devices connected to NT computers can coexist
with Unix devices connected to Unix computers. With fabrics, some ports
can be shared across zones. As a common port, a tape library could
backup both NT and Unix systems. However, this is not possible with
loops, due to the nature of how the arbitrated loop protocol functions.
Some advantages of zoning include:
• Disturbances outside of the zone do not affect devices within the zone.
• When backing up to a tape drive, an application will not lose
communication with the tape drive when other ports on the system
outside of the zone are turned on or off.
• Zoning can be done dynamically, allowing an application to select only
the devices for communication, which increases the reliability of the
overall system.
NOTE Not all systems and subsystems support zoning. Use of this feature is
limited to architectures designed for it. HP Fibre Channel libraries do
not need additional features to function in a zoned environment.