Cross-invalidation activity detail report

The cross-invalidation report presents buffer refresh events due to cross invalidation summarized by selected OMEGAMON for DB2® Performance Expert identifiers. If two DB2 systems compete for read/write interest on a page set or partition, a certain amount of buffer cross-invalidation activity occurs to maintain DB2 buffer pool coherency between the two systems.

Cross-invalidation (XI) renders a higher percentage of the buffer pool data invalid. It has the effect of reducing the buffer pool size and thus the buffer pool hit ratio. Buffer pool pages must be continually refreshed when high cross-invalidation levels are reached. This can be a significant overhead in data sharing if workloads between DB2 systems are not properly balanced.

The following command produces the cross-invalidation report in I/O Activity Cross-Invalidation Report. 

 
IOACTIVITY
     REPORT
        LEVEL (XI)

I/O Activity Cross-Invalidation Report

   LOCATION: LOCATION1                  OMEGAMON XE FOR DB2 PERFORMANCE EXPERT (V5R4M0)                   PAGE: 1-1
      GROUP: GROUP1                      I/O ACTIVITY REPORT - CROSS INVALIDATION               REQUESTED FROM: NOT SPECIFIED
     MEMBER: MEMBER1                                                                                        TO: NOT SPECIFIED
  SUBSYSTEM: DB2A                            ORDER: INTERVAL-PRIMAUTH-PLANNAME                   INTERVAL FROM: 01/30/15 18:50:00.00
DB2 VERSION: V10                                                                                            TO: 01/30/15 20:50:00.00

INTERVAL
 PRIMAUTH                                                                             -SYNCHRONOUS READS-   -SEQUENTIAL PREFETCHES-
  PLANNAME            PAGE                                                              GBPOOL       DASD       GBPOOL       DASD
--------------------  -------------------------------------------------------------   --------   --------     --------   --------

01/30 18:50 - 01/30 18:55
 AUTH_10
  PLAN_10
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000002' BPID=BP22            1          0            0          0
01/30 18:55 - 01/30 19:00
 AUTH_10
  PLAN_10
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000002' BPID=BP22            3          0            0          0

01/30 19:00 - 01/30 19:05
 AUTH_10
  PLAN_10
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000002' BPID=BP22            1          0            0          0
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000004' BPID=BP22            1          0            0          0

                      *SUM OF PLAN_10*                                                       2          0            0          0

01/30 19:05 - 01/30 19:10
 AUTH_10
  PLAN_10
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000002' BPID=BP22            0          1            0          0
                      DB=4        OB=2        PIECE#=0  PAGE#=X'000004' BPID=BP22            2          0            0          0

                      *SUM OF PLAN_10*                                                       2          1            0          0

 .
 .
 .
*** GRAND TOTAL ***                                                                         19          4            2          0

I/O ACTIVITY REPORT COMPLETE

Column description

The following is a description of each column printed in the cross-invalidation report:
OMEGAMON for Db2 Performance Expert Identifiers
The XI report presents data summarized by OMEGAMON for Db2 Performance Expert identifiers. The report can be ordered by up to three OMEGAMON for Db2 Performance Expert identifiers. The identifiers used to sort the report are printed in the leftmost column. They are printed whenever they change. The second and third identifiers are indented to appear under the relevant column subheading.
Note: Blank or null OMEGAMON for Db2 Performance Expert identifiers are denoted by the word 'BLANK'.
PAGE
The name of the page involved in the cross invalidation. The name consists of the following parts:
DB
Database name
OB
Page set name
PIECE#
Page set piece number
PAGE#
Page number
BPID
Buffer pool ID

If DATABASE or PAGESET are selected in the ORDER option, DB or OB are not shown as part of the page name.

SYNCHRONOUS READS
The number of times the page was refreshed via a synchronous read for a particular combination of OMEGAMON for Db2 Performance Expert identifiers and cross-invalidated page:
GBPOOL
From the group buffer pool.
DASD
From the DASD.
SEQUENTIAL PREFETCHES
The number of times the page was refreshed via a sequential prefetch for a particular combination of OMEGAMON for Db2 Performance Expert identifiers and cross-invalidated page.
GBPOOL
From the group buffer pool.
DASD
From DASD.
SUM OF
The totals for all pages within a combination of OMEGAMON for Db2 Performance Expert identifiers if two or more entries are printed in the PAGE column.
SUBTOTAL
When a report is ordered by three identifiers and there is more than one third-level identifier reported under it, a subtotal is printed each time the second-level identifier changes.
TOTAL
When a report is ordered by two or three identifiers and there is more than one second-level identifier reported under it, a total is printed each time the first-level identifier changes.
GRAND TOTAL
A grand total is printed at the end of each location if there is more than one first-level identifier reported.