SAP Note

Header Data

Symptom

A DB2 for z/OS subsystem that hosts an SAP system is migrated from V8 to V9 or a new DB2 V9 for z/OS subsystem is installed to host an SAP system.

Other Terms

DB2, z/OS, V9, Migration, Upgrade, ZPARM, System parameter, GROUP ATTACH

Reason and Prerequisites

-

Solution

As DB2 V9 introduces many enhancements that benefit SAP systems, some of the SAP recommendations for DB2  V8 system parameters that were given previously need to be adapted and complemented by additional recommendations. This note summarizes the recommended values for the DB2 V9 system parameters, buffer pool settings and DBM1 virtual storage estimates for all SAP releases. We recommend that you keep system parameters set to their default values if not otherwise stated in this SAP Note. To ease migration to DB2 V9, system parameters are mentioned here even if the default values are recommended in case this value was not the default in DB2 V8. More detailed information on the recommended DB2 V9 system parameters are given in the SAP Database Administration Guide for DB2 for z/OS for the SAP releases 6.40, 7.00 and 7.10. This SAP Note also describes how to deal with the randomized GROUP ATTACH processing of DB2 V9. This only applies to SAP systems using ICLI or application servers on z/OS. --------------------------------------------------------------------- Required Parameters:

l ASCCSID          819

l SCCSID           SAP <= 640: Any value where DB2 supports                             bijective translation between                             SCCSID and ASCCSID and that                             supports the EBCDIC invariant                             character set                 SAP >= 700: Any SCCSID for which DB2 supports                             a round-trip conversion to                             ASCSSID 819 for the following                             characters:                             0123456789                             ABCDEFGHIJKLMNOPQRSTUVWXYZ                             _#$~^

l DECIMAL          . (Always use a period (.) and never                     a comma (,))

l CTHREAD          The setting of CTHREAD is highly dependent on                 the overall environment size of the SAP system.                 CTHREAD should be at least equal to the sum of                 TSO users and IDBACK

l IDBACK           >= 20 and at least 30% higher than the sum of:                 - SAP work processes that use ICLI                 - SAP work processes that run on z/OS                 - Alert router threads of RFCOSCOL or SAPCL

l MAXDBAT          >= 100 and at least 30% higher than the sum of:                 - SAP work processes that use DB2 Connect

    1032273 - DB2-z/OS: Configuring DB2 V9  

Version   27     Validity: 08.11.2010 - active   Language   English

Released On 08.11.2010 15:08:02

Release Status Released for Customer

Component BC-DB-DB2 DB2 for z/OS

Priority Recommendations / Additional Info

Category Consulting

                - Secondary connections that use DB2 Connect

l IDTHTOIN         0

l PRGSTRIN         DISABLE (introduced by APAR PK46079, if the                 connection property progressiveStreaming is set                 to 2, the ZPARM PRGSTRIN can also be set to                  ENABLE)

l Catalog sequence DSNSEQ_IMPLICITDB: 10000                 APAR PK62178 introduces this sequence.                 For new DB2 V9 subsystems that were installed                 with APAR PK62178 applied, this catalog                 sequence defaults to 10000.  If the DB2 V9                 system was installed prior to APAR PK62178, it                   defaults to 60000. In this case, the ALTER                 SEQUENCE SQL statement on the sequence                 DSNSEQ_IMPLICITDB needs to be issued once with                  the value 10000.

l CMTSTAT          INACTIVE (DB2 V9 default)

--------------------------------------------------------------------- Highly Recommended Parameters:

l NUMLKUS          2097152

l NUMLKTS          1000000 (1 mio.)

l IRLMRWT          600

l EVALUNC          YES

l CONTSTOR         YES

l CONDBAT          Set CONDBAT to the same value as MAXDBAT

l DEADLOK          5.1 (if there are relatively few locks and many deadlocks, this may be set to lower values like 1.1 - before changing, monitor the number of deadlocks)

l MONSIZE          500000

l NPGTHRSH         10

l LOBVALA          SAP >= 620: 1 GB

l LOBVALS          SAP >= 620: 50 GB

l STARJOIN         2

l SJTABLES         4

l MAX_OPT_CPU      2

l MXQBCE           1023

l MXDTCACH         128 MB(up to 256 MB if sufficient real storage)

l EDMPOOL          Value recommended by DB2 installation CLIST                  should be accepted.                 In any way, at least 64000 KB

l EDMDBDC          Value recommended by DB2 installation CLIST                  should be accepted.                 In any way, at least 150000 KB

l IMPDSDEF         NO

l IMPTSCMP         YES

l TBSBPOOL         BP2

l IDXBPOOL         BP3

l TBSBPLOB         BP40

l TSQTY            144

l IXQTY            144

l MGEXTSZ          YES (DB2 V9 default)

l RRF              DISABLE (introduced by APAR PK87348)

--------------------------------------------------------------------- Recommended Parameters:

l EDMSTMTC         300000 KB

l MAXKEEPD         <= 8000

l SRTPOOL          >= 28000 KB                 With SAP BW: >= 64000 KB

l MAXRBLK          >= 100000

l CHKFREQ          2 minutes

l DSMAX            20000

l RETLWAIT         1

l UTIMOUT          3

l URCHKTH          1

l URLGWTH          100 K

l XLKUPDLT         TARGET

l SMFACCT          1,2,3

l SYNCVAL          30

l SEQCACH          SEQ

l LBACKOUT         NO (may be set to AUTO if ramifications known)

l PARAMDEG         Number of available CPUs

l PCLOSET          25

l PCLOSEN          15

l MLMT            4 GB (needs to be backed by real storage)

l DDF              SAP >= 620: AUTO

l ACCUMACC         SAP >= 620: 5

l ACCUMUID         11

l LRDRTHLD         10

l SYSTEM_LEVEL_BACKUPS YES

l STATROLL         YES

l MINSTOR          YES (DB2 V9 default)

l CACHEDYN_FREELOCAL 1 (DB2 V9 default)

l OPTIXOPREF       ON (introduced by APAR PK51734)

l EN_PJSJ          ON (introduced by APAR PK76100)

l STATCLUS         ENHANCED (DB2 V9 default)

l OPTHYBCST        ON (introduced by APAR PK90334)

l OPTOIRCPF        ENABLE (introduced by APAR PK89637)

l CHECK_FASTREPLICATION REQUIRED (introduced by APAR PM19034)

--------------------------------------------------------------------- Recently added DB2 parameters: The following DB2 system parameters were recently introduced by DB2 APARs. It is recommended to keep the default values for these parameters. These parameters are listed here for your awareness of new system parameters.

l ACCEL              NO

l DB2SORT            DISABLE

l DRDA_RESOLVE_ALIAS NO

l PARA_EFF           100

l PREVALKEEP         NO

l WFDBSEP            NO

l XMLTABJPD          NO

--------------------------------------------------------------------- Buffer Pool Setting Recommendations: If there is sufficient real storage available, it is recommended to set the buffer pool attribute PGFIX=YES. Note that this must not be set if the buffer pools are not always backed by real storage. If there are compressed indexes, these indexes should be backed by a separate bufferpool with PGFIX=NO. There is no benefit in page fixing this bufferpool, because there is a special I/O work area for these objects that is always page-fixed.

l BP0 (DB2 catalog):   VPSIZE=2000,  VPSEQT=50, DWQT=50, VDWQT=10

l BP1 (4K work files): VPSIZE=15000, VPSEQT=99, DWQT=50, VDWQT=10

l BP32K3 (32K work files):                     VPSIZE=15000, VPSEQT=99, DWQT=50, VDWQT=10

l BP2 (4 KB TS):       VPSIZE=82000, VPSEQT=50, DWQT=30, VDWQT=5

l BP3 (index spaces):  VPSIZE=120000,VPSEQT=40, DWQT=30, VDWQT=5

l BP4 (VB protocol):   VPSIZE=1000,  VPSEQT=10, DWQT=70, VDWQT=50

l SAP >= 620: BP40 (LOB TS)        VPSIZE=4000,  VPSEQT=50, DWQT=50, VDWQT=10

l BP8K0 (8KB TS+CAT):  VPSIZE=3000,  VPSEQT=50, DWQT=30, VDWQT=5

l SAP >= 7.1: BP8K1 (VB protocol)  VPSIZE=1000,  VPSEQT=10, DWQT=70, VDWQT=50

l BP16K0 (16KB TS+CAT):VPSIZE=3000,  VPSEQT=50, DWQT=30, VDWQT=5

l BP32K (32KB TS+CAT): VPSIZE=5500,  VPSEQT=50, DWQT=30, VDWQT=5

--------------------------------------------------------------------- DBM1 Virtual Storage Consumption Below the 2 GB Bar With DB2 V9, some storage structures reside below the 2 GB bar. The average sizes of these structures in SAP environments are as follows. Note that the actual sizes may vary. Therefore, it is beneficial to leave sufficient headroom of 300 MB.

l Per DB2 thread:             2.5 MB

l Per open data set:          1.5 KB

l System storage:             Non-data sharing 124 MB                             Data sharing     237 MB

l RID pool:                  MAXRBLK * 0.25

l EDM pool:                  EDMPOOL * 0.75

l SQL statement in local DSC:                     0.4 * (M * 3.5 KB + MAXKEEPD * 1.1 * 40 KB)                         (M is the larger value of MAXKEEPD * 1.1                         and the max. number of statements in                         the EDM statement cache. Avg. statement                         size in EDM statement cache is 30 KB)

l Storage cushion:            LPVTSOS + LPVTCRIT + LPVTMVS with          LPVTMVS (storage for MVS) = (DSMAX * 1300)                                     / 1024 * 1024 + 40K          LPVTSOS (cushion warning) = MAX (5% of Extended Region                                           Size, LPVTMVS)          LPVTCRIT (storage for must complete) = (CTHREAD                                           + MAXDBAT + 1) * 20K

As a general starting point, you may assume to accomodate roughly 400 threads in an individual DB2 subsystem. To control the number of database connections that are opened from a single Java node in the JDBC connection pool, you can adapt the following properties of the Java system datasource:

l sysDS.maximumConnections

l sysDS.initialConnections (Note: when an application requests a new connection and no connection is available in the pool, then the connection pooling mechanism creates sysDS.initialConnections new connections)

l sysDS.connectionLifetime

l sysDS.maxTimeToWaitConnection

l sysDS.runCleanupThreadInterval

--------------------------------------------------------------------- Randomized GROUP ATTACH processing with ICLI or SAP app servers on z/OS This step only applies to SAP systems using ICLI or SAP application servers running on z/OS. DB2 V9 randomizes the GROUP ATTACH processing for local applications in case two or more DB2 data sharing members run on the same z/OS LPAR. As this behavior dos not fit to the application-controlled failover approach, GROUP ATTACH should not be used with DB2 V9. You should rather explicitly specify the subsystem ID for each DB2 member used by SAP systems. Required settings for SAP BI systems on DB2 V9 (for details see note 1149824) Set the RSADMIN parameter DB2_HISTOGRAM_NUMCOLS  to 1 or apply the correction of  the corresponding SAP note 1000587. Otherwise the optimizer will choose bad plans for some queries.

Validity

References

This document refers to:

SAP Notes

This document is referenced by:

SAP Notes (12)

Software Component From Rel. To Rel. And Subsequent

DB2 9 9  

1426172   DB2-z/OS: Connection Profile for SAP Java Stack

1399929   DB2-z/OS: Avoiding automatic recommendations for REORG

1398993   DB2-z/OS: Running two or more DB2 members on one z/OS LPAR

1339644   DB2-z/OS: DB2 Connect 9.1 JDBC Failover for SAP Java stack

1085521   DB2-z/OS: Seamless JDBC Database Failover for SAP Java stack

1043951   DB2-z/OS: Release of DB2 V9 for SAP Components

536074   DB2-z/OS: BI: Configuring buffer pools for SAP BI

534036   SAP LT: System settings for conversions

427748   DB2-z/OS: CCMS corrections (6.10, 6.20, 6.40, 7.x)

217093   DB2 z/OS: CCMS transports for 4.6C

81737   DB2-z/OS: APAR List

536074   DB2-z/OS: BI: Configuring buffer pools for SAP BI

534036   SAP LT: System settings for conversions

1085521   DB2-z/OS: Seamless JDBC Database Failover for SAP Java stack

1426172   DB2-z/OS: Connection Profile for SAP Java Stack

717215   DB2-z/OS: DB2 V8 configuration for SAP rel. <= 4.6D

1399929   DB2-z/OS: Avoiding automatic recommendations for REORG

1398993   DB2-z/OS: Running two or more DB2 members on one z/OS LPAR

1339644   DB2-z/OS: DB2 Connect 9.1 JDBC Failover for SAP Java stack

1043951   DB2-z/OS: Release of DB2 V9 for SAP Components

427748   DB2-z/OS: CCMS corrections (6.10, 6.20, 6.40, 7.x)

217093   DB2 z/OS: CCMS transports for 4.6C

81737   DB2-z/OS: APAR List