4. EXCEPTIONS › 4.3 Detailed Exception Descriptions › 01102: Selector Channel Underutilized

01102: Selector Channel Underutilized

    FILE: Physical Channel Activity File
    SAS FILE NAME: DAYS.HARPCA01
    SOURCE LOCATION: prefix.MICS.USER.SOURCE(DYRMFEXC)

    SEVERITY: Warning              (SEVERITY='W')
    MANAGEMENT AREA: Performance   (MGMTAREA='PERFORMANCE')

    PURPOSE:  Identify underutilized selector channels which
identify wasted resources or indicate a potential channel
bottleneck.

    RATIONALE:  During periods when work is expected in the
system, low channel utilization suggests that external
effects (that is, RESERVES) may be preventing proper
utilization.  If low channel utilization occurs on one
channel concurrent with high utilization on the other
channels, some external impact (that is, high paging) may be
the cause.  Low utilization can also be due to an imbalance
caused by an improperly specified channel selection
algorithm.

    DEFINITION:  This exception is detected when the channel
busy percentage is below the installation defined minimum.  A
selector channel is underutilized when its channel busy
percent is below 10% during expected heavy load hours.

    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:

** 01102 SELECTOR CHANNEL UNDERUTILIZED;
*;
IF CHANTYPE='SELECTOR'
 AND PCAPCBSY < percent
 AND (DAYNAME='MON' OR DAYNAME='TUE' OR DAYNAME='WED'
      OR DAYNAME='THU' OR DAYNAME='FRI')
     AND (HOUR >= hh1 AND HOUR <= hh2)
 THEN DO;
  EXCCODE='01102'; SEVERITY='W'; MGMTAREA='PERFORMANCE';
  EXCDESC1='SELECTOR CHANNEL UNDERUTILIZED';
  EXCDESC2='BUSY=' || PUT(PCAPCBSY,5.1) ||
        '%, CHAN=' || CHANNEL;
  IF RMFVER<='08 '
    THEN EXCDESC2=TRIM(EXCDESC2) || ', SET=' || CPUID;
  LINK HIT;
END;

    THRESHOLD MODIFICATION:  The user should modify the
percent value and prime time according to the following
conventions:

    percent - The channel busy percent is specified.  A 10
percent threshold would appear as:

    PCAPCBSY < 10

    prime time - The hour range and days of the week to be
included in the exception are specified.  The hour of the day
must be within the hh1 through hh2 range.  Prime time
specified as 8am through 6:59 pm (18:59) would appear as:

    AND ( 8 <=HOUR AND HOUR<= 18 )

The days of the week are represented by the first three
characters of their names.  They must be enclosed in quotes,
separated with OR's.  Prime time specified as MONDAY through
FRIDAY would appear as:

    AND (DAYNAME='MON' OR DAYNAME='TUE' OR DAYNAME='WED'
         OR DAYNAME='THU' OR DAYNAME='FRI' )

The time period to be included may already be defined by
means of the ZONE definition, which would provide a simpler
method of selecting hours and days for processing.  If ZONE 1
corresponds to the desired time period, it would appear as:

    AND ZONE='1'