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Oracle Performance Tuning and Optimization
(Publisher: Macmillan Computer Publishing)
Author(s): Edward Whalen
ISBN: 067230886x
Publication Date: 04/01/96

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Network

By making sure that you have a sufficient amount of packet-receive buffers, you avoid dynamically allocating them at run time. The packet-receive buffers are used to buffer the incoming network requests while the processor is busy. The number of packet-receive buffers is controlled by the NetWare parameter MINIMUM PACKET RECEIVE BUFFERS. This parameter is set in STARTUP.NCF. A good starting point is 200 (sufficiently high for about 40 users or fewer).

By monitoring the packet-receive buffers on the NetWare monitor screen, you can see whether they are being dynamically allocated. If the number of packet-receive buffers frequently exceeds the value you have set for MINIMUM PACKET RECEIVE BUFFERS, consider increasing this value. If you never achieve more than the minimum, you may be wasting space. By having the value too high, memory is wasted.

Try setting the value of MINIMUM PACKET RECEIVE BUFFERS down a little until you begin to see dynamic allocation at run time. At this point, increase the value of this parameter by 2 to 5 percent and monitor it on a regular basis. If dynamic allocation starts again, increase MINIMUM PACKET RECEIVE BUFFERS until that dynamic allocation stops.

SPX/IPX

To increase the number of connections that can be connected through SPX/IPX, increase the value of the Oracle parameter SPX_MAX_CLIENTS. Set this parameter to the maximum number of concurrent user connections required. If more users attempt to connect, they get an error message from SQL*Net.

If you get timeouts from the SPX listener threads, you may have to increase the value of the Oracle initialization parameter SPX_LISTENERS. An Oracle listener is responsible for spawning server processes on behalf of the user connection. SPX timeouts can occur when too many users try to connect at once.

TCP/IP

Under most circumstances, TCP/IP does not require any tuning. TCP/IP does not perform as well as SPX/IPX under NetWare but may be the best solution for you if other machines in your network are running TCP/IP. TCP/IP can be used for Oracle both independently or with SPX/IPX.

I/O Subsystem

As is true for all operating systems, it is very important to ensure that your performance is not bound by physical I/O rates. Be sure that random I/Os do not exceed the physical limitations of your disk drives. Refer to Chapters 14 and 15 for more details.

With NetWare, Asynchronous I/O (AIO) is always enabled. There is no need to adjust tuning parameters to ensure that AIO is enabled.

The default block size for Oracle on NetWare is 4096. This may be sufficient. If your data access patterns are primarily random, and the number of columns in a row is moderate to small, you may benefit by reducing the DB_BLOCK_SIZE to 2048. Doing so causes less data to be retrieved in each I/O and saves space in the SGA by having a smaller block buffer size.

If you have a mix of sequential and random data, and the row size is relatively large, you may be better off leaving the block size at 4096. Although the blocks take up more space in the SGA, the number of I/Os is significantly reduced. It doesn’t take much more overhead and time to retrieve 4K of data from disk than it does to get 2K of data.

At the other extreme, if your data access is primarily sequential, you may benefit by setting the DB_BLOCK_SIZE to 8192. Because sequential access to the database reads the next block anyway, having a larger block size ensures that the database block is already in the SGA. If your data access is random, you end up using up unnecessary space in the SGA. The value you choose for the block size affects performance, either for the better or the worse. If you are unsure, leave the parameter at the default of 4096.

NetWare Summary

There are several ways you can improve the performance of Oracle on your NetWare system. NetWare is a robust, low-overhead operating system that may be the best solution for your RDBMS needs. With the new addition of NetWare SMP, you may be able to achieve highly scaleable performance by adding additional CPUs.

The preceding sections have described various parameters you can adjust in the NetWare operating system and in Oracle itself; a few Oracle parameters are unique to NetWare. The most important area of tuning in NetWare is the amount of memory that can be dedicated to Oracle. You can maximize the memory available to Oracle by reducing the need for memory in other areas of NetWare. You also saw how to increase network performance by reducing dynamic allocation of buffers. Finally, you looked at how to maximize I/O usage by carefully choosing the correct block size.

Use these tuning guidelines in conjunction with other guidelines described in Chapters 9 and 10 to maximize the performance of the Oracle server. Tuning the server operating system in conjunction with the application and client results in the best-performing system possible.

Windows NT

Microsoft Windows NT is a relatively new OS that has quickly gained in popularity. Windows NT has file and print services similar to those offered by NetWare, but Windows NT is primarily used as an application server or client operating system. Windows NT comes in two varieties: NT Workstation and NT Server.

The NT Workstation product is designed for the client users and does not contain many of the management pieces that come standard with the NT Server product. The NT Server product includes the management tools necessary for maintaining a server.

Windows NT is a multiprocessor operating system and can take advantage of scaleable performance increases by adding additional CPUs.

As is NetWare, Windows NT is a server operating system. There is no facility within Windows NT to provide login functionality from terminals. From the very beginning, Windows NT has been designed to support clients over network connections. Unlike NetWare, Windows NT has much more functionality within the server itself.

The Windows NT operating system provides functionality such as 16-bit Windows application support and a GUI. Windows is very easy to manage using these graphical tools. But because of this additional functionality, Windows NT has greater overhead than NetWare.


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