4. EXCEPTIONS › 4.3 Detailed Exception Descriptions › 02503: Pages Transferred Per Physical I/O Below Min

02503: Pages Transferred Per Physical I/O Below Min

FILE: Page/Swap Data Set Activity File
SAS FILE NAME: DAYS.SCPPSD01
SOURCE LOCATION: prefix.MICS.USER.SOURCE(DYRMFEXC)

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

PURPOSE:  Identify page/swap data set delays.

RATIONALE:  The Auxiliary Storage Manager (ASM) dynamically
changes the number of pages transferred per I/O based on the
average service time previously received by the ASM for
earlier page I/O.  This exception identifies those times when
the number of pages is too low, which usually results from
overcommitted paging (insufficient memory or I/O bottlenecks
on the paging device/control unit/channels).

DEFINITION:  This exception is detected when the number of
pages transferred for each paging I/O is less than 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:

**  02503 PAGES TRANSFERRED PER PHYSICAL I/O BELOW MIN
*;
IF PSDPST NE 'SWAP' AND PSDSIO GT 0 THEN DO;
RATE=PSDPGX / PSDSIO;
IF RATE LT rate
   THEN DO;
    EXCCODE='02503';SEVERITY='I';MGMTAREA='PERFORMANCE';
    EXCDESC1='PAGES TRANSFERRED PER PHYSICAL I/O BELOW MIN ';
    EXCDESC2='RATE=' !! PUT(RATE,5.1) !!
            ', VOL=' !! VOLSER !! '(' !! PUT(DEVNUM,HEX4.)!!
           '), DSN=' !! PSDDSN;
    LINK HIT;
  END;
END;

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

rate - The minimum number of pages transferred by I/O is
specified.  A threshold rate of 2 would appear as:

RATE LT 2