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Dual Gripper Commands for an Automated Tape Library

IP.com Disclosure Number: IPCOM000121906D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 96K

Publishing Venue

IBM

Related People

Britton, TG: AUTHOR [+3]

Abstract

This article describes a set of commands for a dual-gripper accessor in an automated tape library (ATL) that enable optimized performance. In addition, this article describes a method of queueing commands to the accessor that provides optimized performance.

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

Dual Gripper Commands for an Automated Tape Library

      This article describes a set of commands for a
dual-gripper accessor in an automated tape library (ATL) that enable
optimized performance.  In addition, this article describes a method
of queueing commands to the accessor that provides optimized
performance.

      An ATL contains tape drives, cartridge storage racks and an
accessor that transports cartridges between the storage racks and the
drives.  Other units may be included in an ATL, but are not relevant
to this article.

      The ATL receives mount and dismount commands for the tape
drives in the library from a host computer.  The ATL control computer
parses these commands and issues commands to perform these mounts and
dismounts to the accessor in the ATL.  The accessor performs the
physical motions that are received from the control computer.

      Dual grippers are provided on the accessor to allow it to
handle more than one cartridge at a time.  Dual grippers allow a
cartridge to be carried in one gripper while another cartridge is
fetched by the other gripper.  The carried cartridge can then replace
the fetched cartridge to complete a cartridge "swap".

      The commands that an ATL can use to process cartridges with
dual grippers are:
      *    GFR - Get a cartridge from a storage rack
      *    PTR - Put a cartridge to a storage rack
      *    SAR - Swap cartridges at a storage rack
      *    GFD - Get a cartridge from a drive
      *    PTD - Put a cartridge to a drive
      *    SAD - Swap cartridges at a drive

      The dual-gripper optimization is illustrated in the following
example:
      *    Single-Gripper Operation

      If the host wanted to dismount a cartridge for a drive and then
mount a cartridge into the same drive, a single-gripper system would
have to perform the following steps:
      -    Move to drive
      -    GFD - Get the cartridge to be dismounted from the drive
      -    Move to first rack position
      -    PTR - Put the dismounted cartridge into the rack
      -    Move to second rack position
      -    GFR - Get the cartridge to be mounted from the rack
      -    Move to drive
      -    PTD - Put the cartridge into the drive
      *    Dual-Gripper Operation

      A dual gripper system would accomplish the same task by:
      -    Move to second rack position
      -    GFR - Get the cartridge to be mounted from the rack
      -    Move to drive
      -  ...