Sun Microsystems StreamLine SL8500 - Manual (Page 60)

Library Complex
20 StreamLine™ SL8500 Modular Library System User's Guide • March 2007 Revision K • 96154
Pass-thru Ports
A PTP is an electro-mechanical device that allows one Library Storage Module (LSM) to
pass a cartridge to another library storage module within the same complex.
For example: If an operating system issues a mount request, and all the tape drives are
busy in that LSM and library, the PTP can pass the cartridge to another library where
an idle tape drive can satisfy the mount request.
There are eight PTP locations in an SL8500 library, two locations per rail (or LSM).
These locations are on the curved portions of the Robotic Interface Module near the
tape drives. Therefore, they provide quick access to the drives.
The SL8500 PTPs consist of a separate frame ( FIGURE 1-8 ) that is installed between the
Drive and Electronics Module and the Robotics Interface Module. Each frame has four
separate PTP mechanisms that can pass up to two cartridges each between LSMs (one
cartridge mechanism) for a total of eight cartridges.
The maximum size of a library complex connected through PTPs is 7 libraries.
Note – Because elevators transfer cartridges from one LSM to another, these transfers
are also pass-through operations. The elevators are thus internal PTPs, considered by
host software to be on Panel 0.
The following terms and definitions apply to SL8500 PTP operations:
FIGURE 1-8 Pass-thru Port
Home library Provides power, signal, and control lines to the PTP mechanisms. This is the
library on the right as viewed from the front.
Away library Always located on the left side of a Home library, as viewed from the front.
Source Contains the home slot location for the cartridge that will be passed through
to an adjacent library.
Destination Contains the tape drive or slot location in the adjacent library where the
cartridge will be mounted or stored.