Browse Prior Art Database

Heuristic Algorithm for Writing a Stand-Alone Dump

IP.com Disclosure Number: IPCOM000102338D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 73K

Publishing Venue

IBM

Related People

Wright, MA: AUTHOR [+2]

Abstract

Disclosed is a method that allows a program to heuristically determine the optimal header and data field sizes for writing a stand-alone dump data set, that avoids configuration- and processor-dependent errors (i.e., overruns).

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

Heuristic Algorithm for Writing a Stand-Alone Dump

       Disclosed is a method that allows a program to
heuristically determine the optimal header and data field sizes for
writing a stand-alone dump data set, that avoids configuration- and
processor-dependent errors (i.e., overruns).

      SADUMP is a stand-alone program that is IPLed after an MVS
failure in order to write the contents of storage into a dump data
set.  SADUMP is required, for compatibility reasons, to write its
dump data sets in 4104 byte records to tape medium.

      The 4104 byte records consist of two noncontiguous fields:
      -    8-byte header (storage key, ASID, virtual or real storage
address)
      -    4096-byte data area (storage from the MVS system being
dumped).

      The header field is constructed in storage that SADUMP sets
aside for its own processing.  The 4096-byte data area is storage
that was in use by MVS when it crashed.  Because the storage
containing the header cannot be contiguous with the MVS storage being
dumped, SADUMP uses the data chaining function of channel command
words to point to the two fields (see Figure 1).

      Data chaining can put a heavy load on the channel. Factors
affecting channel load include:
      -    data address alignment
      -    low CCW-byte counts
      -    high device data-rates
      -    other channel activity within the channel subsystem
      -    additional central storage accesses for CCWs...