4. EXCEPTIONS › 4.3 Detailed Exception Descriptions › 02104: Log Chan / LCU Delayed I/O (Device Busy) Exceeds Max

02104: Log Chan / LCU Delayed I/O (Device Busy) Exceeds Max

    FILE: Logical Channel Activity File
    SAS FILE NAME: DAYS.SCPLCA01
    SOURCE LOCATION: prefix.MICS.USER.SOURCE(DYRMFEXC)

    SEVERITY: Impacting            (SEVERITY='I')
    MANAGEMENT AREA: Performance   (MGMTAREA='PERFORMANCE')

    PURPOSE:  Identify why logical channel or logical control
unit queue exists.

    RATIONALE:  There are four reasons why a queue will form
for the logical channel in an MVS/370 environment:        the
device, control unit, logical channel, or physical channel
can be busy.  In MVS/XA on a 3090 processor, queueing can be
caused by either control unit or a channel path busy
condition, and on other CPUs by either control unit or device
busy conditions.  One of these reasons, device busy, can
indicate incorrect configuration of control units in the I/O
subsystem.

    DEFINITION:  This exception is detected when the percent
of I/O operations deferred because of device busy exceeds the
installation defined maximum.

    EXCEPTION STATEMENTS:  The SAS statements identifying the
exception situation and describing the condition are stored
in the source member named in SOURCE LOCATION and are
described below:

**  02104 LOG CHAN / LCU DELAYED I/O (DEV BUSY) EXCEEDS MAX
*;
IF LCAPCDVB > percent
 THEN DO;
  EXCCODE='02104';SEVERITY='I';MGMTAREA='PERFORMANCE';
  IF RMFVER<='08 ' THEN DO;
    EXCDESC1='LOGCHAN DELAYED I/O (DEVICE BUSY) EXCEEDS MAX';
    EXCDESC2='DELAYED=' || PUT(LCAPCDVB,5.1) ||
        '%, LOG.  CHAN=' || PUT(LOGCHAN,3.);
  END;
  ELSE DO;
    EXCDESC1='LCU DELAYED I/O (DEVICE BUSY) EXCEEDS MAX';
    EXCDESC2='DELAYED=' || PUT(LCAPCDVB,5.1) ||
            '%, LCUID=' || LCUID;
  END;
  LINK HIT;
END;

    THRESHOLD MODIFICATION:  The user should modify the
percent value according to the following convention:

    percent - The maximum percent of time an I/O is delayed
is specified.  A 75 percent threshold would appear as:

    LCAPCDVB > 75