Programming Interface Information: The Monitor Records are intended Programming Interfaces that allow the customer to write programs to obtain services of z/VM.

#### MRSEKSEK

Prolog
Control Block Contents
Storage Layout
Cross Reference

#### MRSEKSEK Prolog

####

####

     DSECT NAME - SEKSEK
     FUNCTION - Map a Monitor record.
     LOCATED By -
            Through the Monitor Control Area
     REFERENCED CONTROL BLOCKS -
            MRRECHDR    Monitor Record Header
     NAME - MRSEKSEK
     DESCRIPTIVE NAME - Monitor Event Record
                        Domain 7 - Seek Domain
                        Record 1 - Seek Data
     DESCRIPTION - Record of access arm movement ("Seek I/O") on a DASD
                   device or of a set paging parameter to a cache device.
                   Generated each time an I/O channel program containing
                   seek commands(s) is executed.
                   This record contains seek data that may enable a
                   user, such as an operating system developer, to tune
                   DASD seek scheduling algorithms.  This record is NOT
                   intended for DASD load balancing.  However, it can be
                   used to tune a cached minidisk to minimize the number
                   of tracks that must be cached.
     NOTES:
     --  Because of the frequency of seek I/O operations, an extremely
         large number of this record will be generated.  For this
         reason, seek-domain monitoring should be limited to specific
         devices or a specific set of devices.
     --  The order in which the records are generated may not be the
         order in which the commands are executed by the device.
     --  The seek may not be executed by a device when there is a
         permanent device error or when branching is done in the channel
         program which bypasses segments.

    MRSEKSEK Control Block Contents

    Offsets
    Dec Hex  Type       Len  Name (Dim)          Description

      0   0  Structure   60  SEKSEK              Start of monitor record
      0   0  Character    0  SEKSEK_MRHDR        Record header. See MRRECHDR for
                                                 details.
      0   0  Character   20  MRHDR
      0   0  Unsigned     2  MRHDRLEN            record length in bytes
      2   2  Unsigned     2  MRHDRZER            field of zeros
      4   4  Unsigned     1  MRHDRDM             domain identifier
      5   5  Unsigned     1  *
      6   6  Unsigned     2  MRHDRRC             record identifier
      8   8  Character    8  MRHDRTOD            Time at which this record was
                                                 built. In time-of-day (TOD) clock
                                                 format. See IBM System 370 XA
                                                 Principle of Operation for
                                                 explanation of format.
     16  10  Character    4  *
     20  14  Character    0  MRHDR_END           End of header
     20  14  Unsigned     4  SEKSEK_RDEVSID      Host subchannel I.D. number
                                                 defined at initialization
     24  18  Unsigned     2  SEKSEK_CALCURCY     Last seek cylinder for previous
                                                 DASD channel program executed.
                                                 RDEVCYL
     26  1A  Unsigned     2  SEKSEK_CALSKCYL     First cylinder requested in seek
                                                 command(s) in this real channel
                                                 program. IORCYL
     28  1C  Unsigned     2  SEKSEK_CALSKHD      First head number requested in
                                                 seek command(s) in this real
                                                 channel program. IORHEAD
     30  1E  Bitstring    1  SEKSEK_CALFLAGS     Flag byte
              1... ....      SEKSEK_IORDWRIT     ON=This is a WRITE channel
                                                 program. OFF=This is a READ
                                                 channel program.
              .1.. ....      *
              ..1. ....      *
              ...1 ....      *
              .... 1...      *
              .... .1..      *
              .... ..1.      *
              .... ...1      *
     31  1F  Bitstring    1  *                   Reserved for IBM use
     32  20  Character    8  SEKSEK_VMDUSER      Userid of requestor of seek
                                                 command(s) in this real channel
                                                 program. If 'SYSTEM', CP is the
                                                 requestor.
     40  28  Unsigned     4  SEKSEK_IORPOSCT     Number of DASD access arm
                                                 position changes within this real
                                                 channel program.
     44  2C  Unsigned     4  SEKSEK_IORPOSSM     Amount of access arm movements
                                                 (displacements). Cumulative total
                                                 of absolute differences, in
                                                 cylinders, between successive seek
                                                 operation within this real channel
                                                 program
     48  30  Unsigned     2  SEKSEK_CALECYL      Final cylinder number (position
                                                 after this real channel program
                                                 completes). IORECYL
     50  32  Unsigned     2  SEKSEK_VDEVDEV      Virtual device number of the
                                                 target device. Not applicable if
                                                 CP is the requestor (i.e.,
                                                 SEKSEK_VMDUSER = 'SYSTEM').
     52  34  Character    8  SEKSEK_CALUSER      Userid of the owner of the
                                                 target device. Not applicable if
                                                 CP is the requestor (i.e.,
                                                 SEKSEK_VMDUSER = 'SYSTEM').
     60  3C  Character    0  SEKSEK_END

    MRSEKSEK Cross Reference

                          Hex           Hex
    Name                 Offset Length Value

    MRHDR                   0     20
    MRHDR_END              14      0
    MRHDRDM                 4      1
    MRHDRLEN                0      2
    MRHDRRC                 6      2
    MRHDRTOD                8      8
    MRHDRZER                2      2
    SEKSEK                  0     60
    SEKSEK_CALCURCY        18      2
    SEKSEK_CALECYL         30      2
    SEKSEK_CALFLAGS        1E      1
    SEKSEK_CALSKCYL        1A      2
    SEKSEK_CALSKHD         1C      2
    SEKSEK_CALUSER         34      8
    SEKSEK_END             3C      0
    SEKSEK_IORDWRIT        1E           80
    SEKSEK_IORPOSCT        28      4
    SEKSEK_IORPOSSM        2C      4
    SEKSEK_MRHDR            0      0
    SEKSEK_RDEVSID         14      4
    SEKSEK_VDEVDEV         32      2
    SEKSEK_VMDUSER         20      8

    This information is
    based on z/VM V4R3.0.

    Last updated on 1 May 2002 at 16:20:33.

    Copyright IBM Corporation, 1990, 2002