Performance Tuning Siebel Software on the Sun Platform

db_block_max_dirty_target=0
db_writer_processes=4
Fast_start_io_target=0
The default value of db_block_max_dirty_target was changed from 4294967294 to
0. Setting this value to 0 disables writing of buffers for incremental checkpointing
purposes. This stops deferred checkpointing and achieves CPU and bus improvements.
The default value for db_writer_processes is 1. Changing db_writer_processes
to 4 starts up four dbwr processes. These three parameter changes drastically reduced
wait times in the database and thus improved <strong>Siebel</strong> overall throughput.
Db_block_size=8K – default value is 2K. An 8K value for <strong>Siebel</strong> is optimal.
DB_BLOCK_LRU_LATCHES=48 – Specifies the upper bound of the number of LRU
latch sets. Set this parameter to a value equal to the desired number of LRU latch sets.
Oracle decides whether to use this value or reduce it based on a number of internal
checks. If the parameter is not set, Oracle calculates a value for the number of sets
based on the number of CPUs. The value calculated by Oracle is usually adequate;
increase this value only if misses are higher than 3% in V$LATCH. For <strong>Siebel</strong> 10,000
users run on a four CPU machine, setting the value to 48 was optimal.
distributed_transactions=0 – Setting this value to 0 disables the Oracle
background process called reco. <strong>Siebel</strong> does not use distributed transactions, meaning
that we can regain CPU and bus by having one less Oracle background process. The
default value is 99.
replication_dependency_tracking=FALSE
<strong>Siebel</strong> does not use replication so it is safe to turn this off by setting it to false.
transaction_auditing=FALSE
Writes less redo for every commit. It is the nature of <strong>Siebel</strong> OLTP to do many small
transactions with frequent commits. Setting transaction_auditing to false buys
back CPU and bus.
Here is the complete listing of the init.ora file used with all the parameters set for
10,000 <strong>Siebel</strong> users.
Oracle 9.2.0.2 init.ora file
# Oracle 9.2.0.2 init.ora for solaris 9, running up to 10000 <strong>Siebel</strong> 7.5.2 user
benchmark.
db_block_size=8192
db_cache_size=3048576000
db_domain=""
db_name=oramst
background_dump_dest=/export/pspp/oracle/admin/oramst/bdump
core_dump_dest=/export/pspp/oracle/admin/oramst/cdump
timed_statistics=FALSE
user_dump_dest=/export/pspp/oracle/admin/oramst/udump
control_files=("/export/pspp/oracle/admin/oramst/ctl/control01.ctl",
"/export/pspp/oracle/admin/oramst/ctl/control02.ctl",
"/export/pspp/oracle/admin/oramst/ctl/control03.ctl")
<strong>Performance</strong> <strong>Tuning</strong> <strong>Siebel</strong> <strong>Software</strong> on the Sun Platform Page 48