Oracle Internet Directory Administrator's Guide
Release 2.1.1

Part Number A86101-01





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Once capacity planning as described in Chapter 14, "Capacity Planning" is complete, and the necessary hardware acquired, it is important to perform some test runs to figure out if the hardware and software combination is yielding the desired levels of performance. This chapter gives guidelines for tuning an Oracle Internet Directory installation. This chapter contains these topics:

About Tuning

The two main performance metrics for any installation of Oracle Internet Directory are:

If the performance tests yield poor results, the performance problems may be identified and fixed using the information provided in the following sections.

Tools for Performance Tuning

Knowledge of the following tools is recommended for Solaris and most other UNIX operating systems:

Tool  Description 


Displays the top CPU consumers on a system 


Shows running statistics on various parts of the system including the Virtual Memory Manager 


Shows an output similar to vmstat but split across various CPUs in the system. This is available on Solaris only. 


Shows the disk I/O statistics from various disk controllers 

Knowledge of the following tools is recommended for Windows NT:

Tool  Description 

Windows NT Performance Monitor 

Provides a customized view of the events in the system 

Windows NT Task Manager 

Provides a high level output (like `top' on UNIX) of the major things happening in the system. 

Knowledge of the following tools is recommended for Oracle8i:

In addition to the operating system tools, the LDAP applications being used in a customer environment must be able to provide latency and throughput measurement.

In addition, the Database Statistics Collection Tool (, located at $ORACLE_HOME/ldap/admin, is provided to analyze the various database 'ods' schema objects to estimate the statistics.

See Also:

"OID Database Statistics Collection Tool Syntax" 

CPU Usage Tuning

The CPU is perhaps the most important resource available for any software. While Chapter 14 gives a rough estimate of the required CPU horsepower for a given application load, sometimes insufficient tuning can cause inefficient use of the CPU resources. Consider tuning CPU resources if either of the following cases is true:

Internal benchmarks show that Oracle Internet Directory performs best when approximately 70 to 75 percent of the CPU resources are consumed by Oracle Internet Directory processes, and the remaining (about 25 to 30 percent) are consumed by the Oracle foreground processes corresponding to the database connections. While monitoring CPU usage, it is also important to monitor the percentage of time spent in the system space compared to user space. Internal benchmarks show best throughput numbers at about 85 percent user and 15 percent system time.

This section contains these topics:

Tuning CPU for Oracle Internet Directory Processes

The demands placed by Oracle Internet Directory processes on the CPU can be controlled by the ORCLSERVERPROCS and ORCLMAXCC parameters. This table lists suggested values for these parameters for various client loads:

500 Concurrent LDAP Clients  1000 Concurrent LDAP Clients  1500 Concurrent LDAP Clients  2000 Concurrent LDAP Clients 

Server processes


10 to 15 

20 to 30 

30 to 40 

40 to 60 

Database connections


10 to 15 

15 to 20 

15 to 20 

15 to 20 

If we take the example of 500 concurrent clients, a value of 10 for ORCLSERVERPROCS with a value of 15 for ORCLMAXCC will result in the following configuration:

Tuning Oracle Internet Directory Processes When CPU Is 100 Percent Utilized

If the CPU usage of the system is at 100 percent, further tuning of the Oracle Internet Directory processes should be considered if both of the following conditions are met:

This condition indicates that the system has too manyOracle Internet Directory server processes and database connections configured. This results in several processes or threads contending for the same CPU resources. As a result, the computer wastes a great deal of time context-switching among runnable tasks. To avoid this, one must systematically decrease the values of ORCLSERVERPROCS and ORCLMAXCC until the best performance for the peak load is achieved and the system and user time are split up as follows:

Tuning Oracle Internet Directory Processes When CPU Is Under-Utilized

If the CPU usage at peak loads is not at 100 percent and the system is idle for a large percentage of the time (that is, more than 5 percent), this indicates that Oracle Internet Directory processes are under-configured and are not making the best utilization of the CPU resources. To solve this problem, one must systematically increase the values of ORCLSERVERPROCS and ORCLMAXCC until the CPU utilization reaches 100 percent and the system and user time are split up as follows:

Tuning CPU for Oracle Foreground Processes

Tuning of CPU resources for Oracle Foreground processes should be considered only if both of the following conditions are met:

If Oracle foreground processes are consuming excessive CPU, it implies that the queries that Oracle Internet Directory is making against the database are using too many CPU cycles. Although there is very little control available to the users on the types of underlying operations performed by the database, the following should be attempted:

Taking Advantage of Processor Affinity on SMP Systems

Several Symmetric Multi-Processor (SMP) systems offer the capability to bind a particular process to a particular CPU. While it is generally a good idea not to bind any process to any processor, it may improve performance if the following conditions are met:

Under the conditions noted above, allowing the database foreground process to run on any CPU can potentially cause many hardware cache misses for other tasks. This is because the database processes need to reference a large amount of data as part of their regular execution, and this often exceeds the limits of L2 caches available on most systems. As a result, when the database process executes on a CPU, most of L2 cache contains pages from the System Global Area (SGA). If a task switch occurs and an Oracle Internet Directory process is activated, all of its fetches from memory will be much slower because the task preceding it on the processor dirtied the L2 cache.

Restricting all of the Oracle foreground processes to execute on only one processor avoids many of the cache misses for Oracle Internet Directory processes. This, in turn, improves the overall performance.

Other Alternatives for a CPU Constrained System

If none of the tips stated in the preceding sections solve CPU related performance problems, the following options are available:

Memory Tuning

After the CPU, memory is the next most important thing to tune. The primary consumer of memory in an Oracle Internet Directory installation is the Oracle8i database. The SGA of the back-end database must be made as large as possible while leaving room for Oracle Internet Directory and Oracle processes to operate their private stacks and heaps. This section provides some details on determining various components of the SGA.

This section contains these topics:

Tuning the System Global Area (SGA) for Oracle8i

The SGA should be sized based on the available physical memory on the system running Oracle8i.

See Also:

Oracle8i Performance Guide and Reference for more information on determining appropriate sizes for the SGA. This book tells how to ensure that the SGA size does not cause increased paging swapping activity. The latter is very detrimental to performance. 

Once the available size of the SGA is determined, two primary tuning items need to be considered:

An initial estimate for the shared pool size is .5 MB per concurrent database connection determined above.

If this estimate consumes more than 30 percent of the total SGA, use 30 percent of the total SGA instead.

Divide 60 percent of the remaining available SGA size by the block size for the database and use this value for the number of DB_BLOCK_BUFFERS. Both of these values should be initial estimates and can be refined using BSTAT/ESTAT and other RDBMS monitoring tools to determine more accurate sizes for best performance.

Other Alternatives for a Memory-Constrained System

If there is insufficient memory to run both the database and the Oracle directory server on the same computer, then one can put the database on a different computer.

Disk Tuning

Balancing Disk I/O is an important consideration in overall RDBMS, and hence Oracle Internet Directory performance. Typically, one can maximize the I/O throughput by using one or more of the following techniques:

This section contains these topics:

Balancing Tablespaces

The Oracle Internet Directory schema is distributed among several tablespaces at installation time for ease of maintenance and performance. Each tablespace contains a grouping of Oracle Internet Directory schema objects appropriate for co-location on disk storage. As available, it is also beneficial to distribute the following objects onto separate logical disks.

See Also:

"RAID" for more discussion about logical disks 

Separate the following:


The information on balancing tablespaces is given in terms of separating Oracle Internet Directory tablespaces onto different logical drives. This assumes that a 'logical drive' is manifested on a separate disk or set of disks from other 'logical drives', and thus represents a division among disks for I/O. (Two logical drives on the same physical disk media do not really provide the same combined I/O throughput of two logical drives located on different physical media.) If a logical drive can be manifest on a striped or RAID disk subsystem, then this may increase the I/O capacity of that logical drive. However, the tablespace locations considered earlier remain applicable when considering, for instance, different logical drives of a volume manager.

Database Tuning

This section describes the other tunable parameters available to an Oracle Internet Directory installation.

The following table gives a quick overview of the recommended values of RDBMS parameters for various client loads. These parameters are configurable in the initialization parameter file.

500 Concurrent LDAP Clients  1000 Concurrent LDAP Clients  1500 Concurrent LDAP Clients  2000 Concurrent LDAP Clients 

Open cursors 










Database block buffers 

200 to 250 MB 

200 to 250 MB 

200 to 250 MB 

200 to 250 MB 

Database block size 





Shared pool size 

30 to 40 MB 

30 to 40 MB 

30 to 40 MB 

30 to 40 MB 






This section describes each of the RDBMS tunable parameters in more detail. It contains these topics:

Required Parameter

Configure the OPEN_CURSORS parameter as follows:


The Oracle8i default of 50 or so is too small to accommodate Oracle Internet Directory server cursor cache. Note that this value is not dependent on other Oracle Internet Directory server parameters, such as # SERVERS and # WORKERS. The value of 100 is sufficient for any size DIT.

Parameters Dependent on Oracle Internet Directory Server Configuration

Configure the SESSIONS parameter as follows:

PROCESSES = (# OID server processes per instance) x 

        (# DB Connections per server + 1) x 
        (# of OID instances) + 20

Each Oracle Internet Directory server process requires a number of concurrent database connections equal to the number of worker threads configured for that server plus one. The total number of concurrent database connections allowed must therefore include this number per server, per instance. The additional 20 connections added to the parameter value accounts for the Oracle background processes plus other Oracle Internet Directory processes such as OID Monitor, OID Control, Oracle directory replication server, and bulk tools.

Using Multi-Threaded Server (MTS)

Depending on the total number of concurrent database connections required, and as determined by the setting for the SESSIONS parameter, enabling MTS may help balance overall system load better. If the total number of concurrent database connections required is over 300, then configure MTS. One shared server should be configured for every 10 database connections required.


The number of requires concurrent database connections depends on the hardware selected. See Net8 Administrator's Guide and Oracle8i Administrator's Guide for further information about MTS configuration. 

SGA Parameters Dependent on Hardware Resources

The main parameters that contribute to the SGA are discussed in "Memory Tuning". The following are a few more parameters that may be tuned:

Performance Troubleshooting

This section gives some quick pointers for common performance related problems.

If LDAP search performance is poor, make sure that:

If LDAP add/modify performance is poor, make sure that:

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