Managing Serviceguard Extension for SAP on Linux (IA64 Integrity and x86_64), April 2009

Database Configuration
This section deals with additional database specific installation steps and contains the following:
• Additional Steps for Oracle
• Additional Steps for MaxDB
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.
More details on these useful High-Availability features can be found both in the Oracle8i and Oracle9i
documentation Oracle8i Designing and Tuning for Performance (Chapter 24: Tuning Instance recovery
Performance) and Oracle9i Database Performance Tuning Guide and Reference Release 2 (9.2).
The following steps have to be performed in order to adjust the Oracle RDBMS setting to the High Availability
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.
Therefore, startdb needs to be adjusted accordingly. Insert / Change the following code within the
/sapmnt/<SID>/exe/startdb file. The sample code can be found in the file:
${SAPSTAGE}/SID/startdb.sql
#
# 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
#
# Startup the database without changing the ARCHIVELOG state
# alter datafile 'end backup' when instance crashed during
Database Configuration 93