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Guidelines for Configuring Settings in the init.ora File

This topic is part of Configuring an Oracle Database for Siebel Applications.

The init.ora file contains parameters that have a major impact on the performance of Siebel applications.

Use the following settings as guidelines for your initial configuration. Your final settings will vary based on the hardware configuration, the number of users, and the type of workload.

In the init.ora file, default parameter values are provided for small, medium, and large Oracle database configurations. Unless the configuration parameters are specified in the following settings, set them to the large database values. Refer to Oracle Database documentation for detailed descriptions of each of the parameters and their effects on database performance and system resource utilization.

Brief descriptions follow for several parameters for which you may need to adjust values:

• CURSOR_SHARING. This parameter is set to EXACT by default and must not be changed. Changing this value may lead to failure of some Siebel Server components.
• DB_BLOCK_SIZE. Small block size leads to high levels of row chaining and large numbers of levels in B*tree indexes, creating serious performance problems. Set the block size to a minimum of 8 KB to prevent excessive row chaining and performance degradation with Siebel EIM.
• DB_CACHE_SIZE. The minimum recommended value is 10,000 blocks (assuming a block size of 8 KB). This value yields 80 MB of block buffers. If significant I/O activity occurs, you can increase this value, if enough RAM is available.

  In a production system, it is recommended that you assign this parameter a minimum value of 400 MB. Also, your system must have a minimum of 1 GB RAM.

  NOTE:  This parameter does not apply if the DBA has set SGA_TARGET.

• DB_FILE_MULTIBLOCK_READ_COUNT. The database buffer cache parameter dictates the number of data blocks read in a single Oracle I/O operation during a table scan.

  For most implementations, set this value between 16 and 32 blocks, and adjust as necessary. You may want to set an initial value of 32. If you are using NAS storage (such as a NetApp Filer), set the value to 8 or 16 to reduce potential network traffic problems.

• NLS_DATE_FORMAT. Set the NLS_DATE_FORMAT parameter as needed. (The default setting is DD-MON-YY.) For information about the formats supported, consult your Oracle Database documentation. For more information, see Specifying the Locale for Siebel Applications.
• NLS_SORT. The sort order is specified during the initial installation of a database and defines the way in which the database sorts character data. Sort order support depends on both the code page of the database and whether it will be used in a development or a production environment. For more information, see Specifying the Locale for Siebel Applications.
  • Development environment databases. Repository object names in your development environment database must sort using binary sort order, because Siebel Tools uses this sort order internally.

    NOTE:  Binary sort order is the simplest and fastest sort order to perform in the database. Binary sorting is case-sensitive and based on the numeric values (for example, 0 through 255 for an 8-bit character set) of characters in the installed character set.

    Specify the same sort order at the database client level, so that output there does not need to be resorted.

    Customers are responsible for making sure that their data is backed up and restored correctly.

  • Production environment databases. For information on production environment database restrictions, see Siebel System Requirements and Supported Platforms on Oracle Technology Network. Also refer to your Oracle Database documentation.
• OPEN_CURSORS. This parameter controls the amount of spaces that will be reserved for the maximum number of cursors (a cursor being the same as an open query). The minimum open cursor requirement for Oracle Database support is 1000 and the maximum is 2000. This parameter may be adjusted according to observed usage patterns.

  Setting this number higher than 2000 commits more memory for the database server, thereby affecting performance. Setting it lower than 1000 can cause an error that prevents you from continuing.

• OPTIMIZER_INDEX_COST_ADJ. Set this parameter to 1. Use it to tune the optimizer to use index access path over a full table scan.
• OPTIMIZER_MODE. Set this parameter to ALL_ROWS, for the Cost-Based Optimizer (CBO).

  NOTE:  For more information about CBO, see 781927.1 (Article ID) on My Oracle Support.

• SHARED_POOL_SIZE. Start with a minimum value of 200 MB in your production environment. The DBA can adjust this value upward based on the available physical memory of the hardware and based on performance.

  Siebel Business Applications make heavy demands on the dictionary cache for columns. For an Oracle database, you cannot explicitly set the size of the column cache. Instead, column cache is set as a fixed percentage of the shared pool size. By setting a large SHARED_POOL_SIZE, you set a large column cache size.

  The number of repositories active in your Siebel schema also adds to dictionary overhead because Siebel Business Applications maintain a record for each column in each table for each repository. As a result, if you have six active repositories, the Siebel dictionary is six times larger than it needs to be.

  NOTE:  This parameter does not apply if the DBA has set SGA_TARGET.

• SORT_AREA_RETAINED_SIZE. Use the default recommended by Oracle. See Oracle Database documentation for details.

  NOTE:  This parameter does not apply if the DBA has set PGA_AGGREGATE_TARGET.

• SORT_AREA_SIZE. This value is specified in bytes, and may be adjusted according to the number of users, the amount of RAM available, and the size of sorted queries. Start with an initial value of 1,000,000 (1 MB). Optimal performance can be achieved for the Dictionary Managed TEMP table spaces if the extents are uniform and a multiple of the SORT_AREA_SIZE.

  NOTE:  This parameter does not apply if the DBA has set PGA_AGGREGATE_TARGET.