4. EXCEPTIONS › 4.3 Detailed Exception Descriptions › 01103: Block Multiplexor Channel Underutilized

01103: Block Multiplexor 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 that
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 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 BlOCK MULTIPLEXOR CHANNEL UNDERUTILIZED;
*;
IF CHANTYPE EQ 'BLOCK MPX' AND
 PCAPCBSY LT percent AND
 (DAYNAME EQ 'MON' OR DAYNAME EQ 'TUE' OR DAYNAME EQ 'WED'
  OR DAYNAME EQ 'THU' OR DAYNAME EQ 'FRI') AND
 (HOUR GE hh1 AND HOUR LE hh2)
 THEN DO;
  EXCCODE='01102'; SEVERITY='W'; MGMTAREA='PERFORMANCE';
  EXCDESC1='BLOCK MULTIPLEXOR CHANNEL UNDERUTILIZED';
  EXCDESC2='BUSY=' !! PUT(PCAPCBSY,5.1) !!
        '%, CHAN=' !! CHANNEL;
  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 LT 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 8:00 am through 6:59 pm (18:59) would appear as:

(HOUR GE 8 AND HOUR LE 18)

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

(DAYNAME EQ 'MON' OR DAYNAME EQ 'TUE' OR DAYNAME EQ 'WED'
OR DAYNAME EQ 'THU' OR DAYNAME EQ '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:

ZONE='1'