Browse Prior Art Database

Fuzzy Network for Dual-Gripper-Picker Library Control

IP.com Disclosure Number: IPCOM000113920D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 162K

Publishing Venue

IBM

Related People

Nelson, DQ: AUTHOR [+3]

Abstract

The picker cycle time of libraries is always under pressure to be reduced. Storing hot cartridges near the devices and cold cartridges far from the devices would help to achieve that. If a library with a dual-gripper picker keeps the old cartridge from the prior dismount until the next mount request comes, the cartridge swap at the storage slot of the new mount request takes more time than merely picking up the new mount request. Similarly, if the target device must first be emptied by the dual gripper picker, then more time is spent loading the new mount request than if the target drive was already empty.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 26% of the total text.

Fuzzy Network for Dual-Gripper-Picker Library Control

      The picker cycle time of libraries is always under pressure to
be reduced.  Storing hot cartridges near the devices and cold
cartridges far from the devices would help to achieve that.  If a
library with a dual-gripper picker keeps the old cartridge from the
prior dismount until the next mount request comes, the cartridge swap
at the storage slot of the new mount request takes more time than
merely picking up the new mount request.  Similarly, if the target
device must first be emptied by the dual gripper picker, then more
time is spent loading the new mount request than if the target drive
was already empty.  At times of low library activity, it may be
desirable to reduce the time to first data by treating the
dual-gripper picker as a single-gripper picker and emptying the
picker and one inactive device in anticipation of the next mount
request.  Alternately, drive, picker, and queue activity may require
leaving the dual-gripper picker as a dual-gripper picker and
performing cartridge swaps at the storage slots (Floating Home Cell)
and the devices.  This will tend to occur during periods of high
library activity.  Thus, a Multiple-Input Multiple-Output (MIMO)
strategy be employed for controlling a dual-gripper picker.

      This article proposes a fuzzy network in which 5 inputs are
used to determine 3 output states for controlling a dual gripper
picker library.  Table 1 shows the descriptions of the network inputs
(U,R,A,Q,E).

Table 1.  Five Network Inputs (U,R,A,Q,E)
  Symbol  Description                     Range
  U       Maximum of average picker       0 <= U <= 1
          utilization or 1 if the         (a continuous function)
          picker is currently busy.
  R       Hits during the past m mounts   1 <= R
          of the old cartridge            (a whole number)
          currently in the picker.
  A       "AND" Function of               0 (at least 1 device
          Activity of each device.             inactive)
          A = (A1) and (A2) and...        1 (all devices active)
  Q       Mount Queue                       0 (no queued mount
requests)
                                          1 (queued mount requests)
  E       "OR" Function of empty devices. 0 (all devices full)
          E = (E1) or (E2) or ...         1 (at least 1 device empty)

      In Table 1, the inputs are the picker utilization U, the
running value of cartridge hits per m mounts R, whether all devices
are active A, whether there is a mount queue Q, and whether any
devices are empty E.

      Use is made of the prefix f to distinguish the fuzzy OR or fOR
operator from the Boolean OR operator.  This classical fuzzy operator...