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Oracle8i Server Installation and Database Administration Guide
Release 3 (8.1.7) for Fujitsu Siemens Computers BS2000/OSD

Part Number A95466-01
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7
Tuning the Oracle Server

Careful tuning can dramatically increase the speed of the Oracle Server on your BS2000/OSD machine. This chapter describes how you can monitor and tune your system for optimal performance of the Oracle Server. For a general discussion of performance and tuning issues, see the Oracle8i Administrator's Guide and Oracle8i Tuning.

This chapter covers BS2000 specific tuning parameters.

You should always tune the Oracle Server system. In addition, you may need to fine tune or reconfigure your BS2000/OSD operating system to achieve optimal performance, or to support more users than the basic configuration will allow.

BS2000/OSD-Specific Parameters

This section describes ORAENV environment variables which have been added for BS2000/OSD-specific Oracle Server performance tuning.

All BS2000/OSD-specific tuning and performance analysis options are controlled by the ORAENV file. No re-linking or patching is required, so it is sufficient to change the value of the environment variable and restart the programs which will be affected by the new settings.

Task Priority

Apart from generic or BS2000/OSD-specific Oracle Server tuning options, the BS2000/OSD priority of Oracle Server tasks at runtime, and their runtime priority balance, can have a lot of influence on the overall throughput and the time delays experienced.

Initially, all foreground (network server) and background tasks have the same runtime priority, as specified by the ORAENV environment variable, BGJPAR. Server tasks automatically become TP tasks, and the background tasks will also switch to TP mode, if the JOIN entry permits this.

Both before and while changing runtime priorities, you should use SM2 to investigate task behavior and possible bottlenecks. There is no simple rule that says that certain tasks always have a high priority.

Initialization Parameters

This section covers the BS2000/OSD-specific aspects (that is, the range and default values) of the initialization file parameters DB_BLOCK_SIZE and DB_FILE_MULTIBLOCK_READ_COUNT.

The value of the initialization parameter DB_BLOCK_SIZE is the size in bytes of an Oracle Server database block. The value of the initialization parameter DB_FILE_MULTIBLOCK_READ_COUNT is the maximum number of blocks read when performing multi-block I/O during a sequential scan. Both parameters are fully documented in the Oracle8i Administrator's Guide.

Parameter Range Default

DB_BLOCK_SIZE

    for 2K pubset format

    for 4K pubset format

    (in INIT.ORA you must express the value in bytes, not in kilobytes)

2K, 4K, 6K, 8K, 16K, 32K

4K, 8K, 16K, 32K

4K

4K

DB_FILE_MULTIBLOCK_READ_COUNT

1-128

1

The optimum value for DB_FILE_MULTIBLOCK_READ_COUNT is the value that corresponds to 32K. For example if DB_BLOCK_SIZE is 4096 then you should set the value of DB_FILE_MULTIBLOCK_READ_COUNT to 8 blocks. Any value larger than that has no advantage on BS2000/OSD.


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