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Application Environment Tuning Policies for Mass Optical Storage Device

IP.com Disclosure Number: IPCOM000100074D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 152K

Publishing Venue

IBM

Related People

Freeman, HL: AUTHOR [+5]

Abstract

Disclosed is a description of the function for setting the operational policies for optical disk drives in an optical library. There are five operational policies, normal, read-only, write-only, read-before-write and write-before-read. A policy can be selected for each drive configured. The operational policies are established when the optical disk drive is configured into the system and may be changed while the optical support is operating.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 45% of the total text.

Application Environment Tuning Policies for Mass Optical Storage Device

       Disclosed is a description of the function for setting
the operational policies for optical disk drives in an optical
library.  There are five operational policies, normal, read-only,
write-only, read-before-write and write-before-read.  A policy can be
selected for each drive configured.  The operational policies are
established when the optical disk drive is configured into the system
and may be changed while the optical support is operating.

      By setting the operational policies to the optical disk drives
within the mass optical storage unit, the user can tune the operation
of the optical library to better meet the needs of the particular
application by optimizing that resource.

      The following set of operational drive policies are provided
for user selection:
 -  Normal:  This policy does not give preference to either optical
reads or writes.
 -  Read-only:  This policy only allows read requests to cause an
optical disk to be loaded onto an optical disk drive.  However, once
an optical disk is loaded, write requests are permitted.
 -  Write-only:  This policy only allows write requests to cause an
optical disk to be loaded into an optical disk drive.  However, once
an optical disk is loaded, read requests are permitted.
-  Read-before-write:  This policy allows both read and write
requests to load an optical disk into an optical disk drive.

      However, when multiple requests are queued, read requests are
given preference.
      -  Write-before-read:  This policy allows both read and write
requests to load an optical disk into an optical disk drive.

      However, when multiple requests are queued, write requests are
given preference.

      An operational policy is selected when the optical disk drive
is configured into the system.  The configured policy is established
each time the optical storage is started. See Fig. 1 for an example
of a configuration screen with drive operational policy selections.

      The user may also change the currently assigned operational
policy during operation of the optical support. See Fig. 2 for an
example of a screen to set drive policies while the system is
operating or while not using the configure utility.

      The following terms are used in the discussion of the optical
disk drive allocation algorithm:
 -  Up-side:  This is the side of an optical disk that is "under" the
optical disk drive read/write mechanism.
      -  Flip-side:  This is the side of an optical disk that is not
"under" the optical disk drive read/write mechanism and the optical
disk must be flipped over before data can be read or written.
      -  Library wait:  A request that has been placed on a wait
queue because the library mechanism is in use processing another
request.
      -  Drive wait:  A request that has been placed on a wait queue
because an op...