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Browse Prior Art Database

Method to Control File Generation under VM/CMS

IP.com Disclosure Number: IPCOM000117391D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 95K

Publishing Venue

IBM

Related People

Benayoun, A: AUTHOR [+5]

Abstract

Many simulators running on VM store the output data of each simulation cycle onto a system disk in a cumulative way (the output data 'run n' is stored just after the output data 'run n-1'). With this method, the output file becomes very large after a few cycles and exceeds the disk capacity. In the same time, performances are degraded. CEFS is an example of such a simulator.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 65% of the total text.

Method to Control File Generation under VM/CMS

      Many simulators running on VM store the output data of each
simulation cycle onto a system disk in a cumulative way (the output
data 'run n' is stored just after the output data 'run n-1').  With
this method, the output file becomes very large after a few cycles
and exceeds the disk capacity.  In the same time, performances are
degraded.  CEFS is an example of such a simulator.

      The idea is to reduce the output file to the last data
generated by the last simulation cycle without modifying and
informing the simulator itself.

      This invention modifies the generation of the output file
stored onto the disk without any modification of the simulator.

The advantages of the current solution are the following:
  o  Save space on disk for specific applications
  o  Save CPU time
  o  Improve performance thruput

Applications of the invention:
  o  Any software programs running on VM that store large quantity of
      bytes on disk run after run

The VM/CMS write system mechanism is summarized as follows:
  o  The simulator application calls the VM/CMS FSWRITE macro to
      perform sequential writes onto the system disk to build the
      output data file.  Each write operation is performed through
the
      FSCB (File System Control Block) which manages the pointers.
      This write operation is labelled (1) in Fig 1.
  o  At the end of a simulation cycle, the FSCB po...