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
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    84  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
       2   2  Unsigned      2  MRHDRZER
       4   4  Unsigned      1  MRHDRDM
       5   5  Unsigned      1  *
       6   6  Unsigned      2  MRHDRRC
       8   8  Character     8  MRHDRTOD
      16  10  Character     4  *
      20  14  Character     0  MRHDR_END
      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
                                                      SEKSEK_CALCURCY is deprecated
                                                      and should not be used for
                                                      further development. Code
                                                      should be changed to use
                                                      SEKSEK_CALCURCY32 defined
                                                      below. For values above
                                                      'FFFF'x then this field will
                                                      contain 'FFFF'x (and will not
                                                      wrap).
      26  1A  Unsigned      2  SEKSEK_CALSKCYL        First cylinder requested in
                                                      seek command(s) in this real
                                                      channel program. IORCYL
                                                      SEKSEK_CALSKCYL is deprecated
                                                      and should not be used for
                                                      further development. Code
                                                      should be changed to use
                                                      SEKSEK_CALSKCYL32 defined
                                                      below. For values above
                                                      'FFFF'x then this field will
                                                      contain 'FFFF'x (and will not
                                                      wrap).
      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
                                                      SEKSEK_IORPOSSM is deprecated
                                                      and should not be used for
                                                      further development. Code
                                                      should be changed to use
                                                      SEKSEK_IOSPOSSM64 defined
                                                      below. For values above
                                                      'FFFFFFFF'x then this field
                                                      will contain 'FFFFFFFF'x (and
                                                      will not wrap).
      48  30  Unsigned      2  SEKSEK_CALECYL         Final cylinder number
                                                      (position after this real
                                                      channel program completes).
                                                      IORECYL SEKSEK_CALECYL is
                                                      deprecated and should not be
                                                      used for further development.
                                                      Code should be changed to use
                                                      SEKSEK_CALECYL32 defined
                                                      below. For values above
                                                      'FFFF'x then this field will
                                                      contain 'FFFF'x (and will not
                                                      wrap).
      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  Unsigned      2  SEKSEK_RDEVDEV         Device number
      62  3E  Unsigned      2  *                      Reserved for IBM use
      64  40  Unsigned      4  SEKSEK_CALCURCY32      Last seek cylinder for
                                                      previous DASD channel program
                                                      executed. RDEVCYL
      68  44  Unsigned      4  SEKSEK_CALSKCYL32      First cylinder requested in
                                                      seek command(s) in this real
                                                      channel program. IORCYL
      72  48  Character     8  SEKSEK_IORPOSSM64
      72  48  Unsigned      4  SEKSEK_IORPOSSM64_HI
      76  4C  Unsigned      4  SEKSEK_IORPOSSM64_LO   Amount of access arm
                                                      movements (displacements).
                                                      Cumulative total of absolute
                                                      differences, in cylinders,
                                                      between successive seek
                                                      operation within this real
                                                      channel program.
      80  50  Unsigned      4  SEKSEK_CALECYL32       Final cylinder number
                                                      (position after this real
                                                      channel program completes).
                                                      IORECYL
      84  54  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     84
    SEKSEK_CALCURCY           18      2
    SEKSEK_CALCURCY32         40      4
    SEKSEK_CALECYL            30      2
    SEKSEK_CALECYL32          50      4
    SEKSEK_CALFLAGS           1E      1
    SEKSEK_CALSKCYL           1A      2
    SEKSEK_CALSKCYL32         44      4
    SEKSEK_CALSKHD            1C      2
    SEKSEK_CALUSER            34      8
    SEKSEK_END                54      0
    SEKSEK_IORDWRIT           1E           80
    SEKSEK_IORPOSCT           28      4
    SEKSEK_IORPOSSM           2C      4
    SEKSEK_IORPOSSM64         48      8
    SEKSEK_IORPOSSM64_HI      48      4
    SEKSEK_IORPOSSM64_LO      4C      4
    SEKSEK_MRHDR               0      0
    SEKSEK_RDEVDEV            3C      2
    SEKSEK_RDEVSID            14      4
    SEKSEK_VDEVDEV            32      2
    SEKSEK_VMDUSER            20      8

    This information is
    based on z/VM V7R2.0.

    Last updated on 08 August 2020 at 20:46:55.

    Copyright IBM Corporation, 1990, 2020