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Reducing Response Time in Optical Libraries Via Deferred Flipping

IP.com Disclosure Number: IPCOM000121190D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 51K

Publishing Venue

IBM

Related People

Willson, LD: AUTHOR [+2]

Abstract

Most optical libraries have drives with only 1 laser, so the desired cartridge volume (side) must be facing towards the laser before being mounted. For the purposes of this disclosure, this required orientation of mounted volumes is in the upwards direction.

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Reducing Response Time in Optical Libraries Via Deferred Flipping

      Most optical libraries have drives with only 1 laser, so the
desired cartridge volume (side) must be facing towards the laser
before being mounted.  For the purposes of this disclosure, this
required orientation of mounted volumes is in the upwards direction.

      Each flip of a cartridge to the desired volume takes
approximately one second.  In a small library, any flipping to the
desired volume is longer than the travel time of the autochanger.  If
any flipping is done serially with cartridge travel, the time to flip
the cartridge on either a demount and/or a mount is directly additive
to the overall mount response time.  So, up to two seconds could be
saved on a mount request if flipping is not necessary on either the
mount or dismount of cartridges.

      A simple and preferred embodiment is to leave the last accessed
volume up.  The probability that a flip of that cartridge will not be
necessary during its mount is equal to the frequency with which that
volume is accessed.

      An alternate and more complicated embodiment entails tracking
the usage of volumes on a daily or weekly running average.  In order
to save time on servicing new mount requests, any flipping of
dismounted cartridges is deferred to a special housekeeping mode.
During quiescent periods in library usage, the more frequently used
(MFU) volume is flipped up in each cartridge's storage slot, as shown
in F...