HP Serviceguard Extension for SAP (SGeSAP) manual Additional Steps for Oracle

Additional Steps for Oracle

The Oracle RDBMS includes a two-phase instance and crash recovery mechanism that enables a faster and predictable recovery time after a crash.

The instance and crash recovery is initiated automatically and consists of two phases:

Roll-forward phase: Oracle applies all committed and uncommitted changes in the redo log files to the affected data blocks. Following parameters can be used to tune the roll forward phase:

•The parameter RECOVERY_PARALLELISM controls the number of concurrent recovery processes.

•The parameter FAST_START_IO_TARGET controls the time a crash / instance recovery may take. Use this parameter to make crash / instance recovery predictable.

Roll-back phase: Oracle applies information in the rollback segments to undo changes made by uncommitted transactions to the data blocks. Following parameters can be used to tune the roll-back phase:

•Fast-Start On-Demand rollback: with this feature Oracle automatically allows new transactions to begin immediately after the roll forward phase of recovery completes. This means that the database will be available again right after the completion of phase one roll-forward. This means that there will be no long waits until long running transactions are rolled back.

•Fast-Start Parallel Rollback: configure the FAST_START_PARALLEL_ROLLBACK parameter to roll-back set of transaction in parallel. This parameter is similar to the RECOVERY_PARALLELISM parameter for the roll-forward phase.

All these parameters can be used to tune the duration of Instance / Crash recovery.

The following steps have to be performed in order to adjust the Oracle RDBMS setting to the HA configuration.

Logon as root to the primary host of the database where the package is running in debug mode.

Oracle Database Step: OR850

Perform the following step as <sid>adm

To ensure that a database that crashed during an online backup starts correctly after the crash, all data files that were in begin backup state need to be altered with an end backup statement. Adjust the required steps in /sapmnt/<SID>/exe/startdb.

Change the following code within the /sapmnt/<SID>/exe/startdb file. The sample code that is to be inserted for different Oracle releases can be found in the files: /opt/cmcluster/sap/SID/startdb.sqlplus and /opt/cmcluster/sap/SID/startdb.svrmgrl

#

#Startup the database without changing the ARCHIVELOG state

echo "connect internal;" > $SRVMGRDBA_CMD_FILE echo "startup;" >> $SRVMGRDBA_CMD_FILE

echo "exit;" >> $SRVMGRDBA_CMD_FILE

eval $SRVMGRDBA command=@$SRVMGRDBA_CMD_FILE >> $LOG 2>&1

Oracle Database Step: OR860

Perform the following steps as ora<sid>.

Configure the listener to listen on the relocatible name of the database package. To do this, change all references from <local> to the relocatible name <relocdb> in the files on the shared volume group. Be careful if these files were customized after the SAP installation. For example:

$ORACLE_HOME/network/admin/listener.ora

$ORACLE_HOME/network/admin/tnsnames.ora

When using Oracle 10g:

/sapmnt/<SID>/profile/oracle/listener.ora

/sapmnt/<SID>/profile/oracle/tnsnames.ora

Oracle Database Step: OR870

Copy $ORACLE_HOME/network/admin/tnsnames.ora to all additional application server hosts.

84 Step-by-Step Cluster Conversion