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Collision-Avoidance Algorithm for Automated Tape Library

IP.com Disclosure Number: IPCOM000105504D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Britton, T: AUTHOR [+3]

Abstract

A method of avoiding collisions of dual accessors in an automated tape library is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Collision-Avoidance Algorithm for Automated Tape Library

      A method of avoiding collisions of dual accessors in an
automated tape library is disclosed.

      An automated tape library consists of tape cartridge storage,
tape drives, and an accessor that moves tapes between the storage and
the drives.  In the library that this disclosure applies to, the
accessor moves down a linear rail with drives and storage on each
side of the rail.

      Library performance can be increased by placing two active
accessors on the same linear rail operating at the same time.  If two
accessors are present, some method to avoid collisions must be
provided.

      Described is a method of avoiding collisions in a dual accessor
library.  This includes a sample layout scheme of the drives and
storage, definition of safety zones, and a technique for collision
avoidance.

      The drives must be located with approximately half of them
assigned to one accessor, and half to the other.  The strings must be
arranged so there is a "dead zone" of an appropriate size so that
each accessor can reach all of its drives without hitting the other
accessor.  If possible, the drives should be clustered towards the
middle of the system.

      A sample layout is shown in the figure.

      The "safe lines" are defined at an appropriate distance past
the last drive in each direction.  An accessor behind the safe line
cannot be hit by the other accessor, no matter what drive it is
accessing.

      The libr...