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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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Hardware Enhancements

In a batch system, several hardware enhancements can help you improve performance. These hardware enhancements can be beneficial in the area of CPU, I/O, and network, as described in the following sections.

CPU Enhancements

Enhancing the CPUs on your SMP or MPP system can provide instantaneous performance improvements—assuming that you are not I/O bound and that you are taking advantage of the Oracle Parallel Query option. The speed of CPUs is constantly being improved as are new and better cache designs.

For SMP or MPP machines, the process of enhancing the CPU may be as simple as adding an additional CPU board. Before you purchase an additional processor of the same type and speed, consider upgrading to a faster processor. Because some batch processing jobs consist of a single job processing the data, you may benefit by purchasing a faster processor rather than more processors. Of course, this depends on your batch jobs and use of the Parallel Query option (refer to Chapter 13, “System Processors”).

SMP and MPP computers provide scaleable CPU performance enhancements at a fraction of the cost of another computer. When upgrading your processors or adding additional processors, remember that your I/O and memory needs will probably increase along with the CPU performance. Be sure to budget for more memory and disk drives when you add processors.

I/O Enhancements

You can enhance I/O by adding disk drives or purchasing a hardware disk array. Batch processing systems can benefit from the disk striping available in hardware or software disk arrays, but the benefit of the disk array is enhanced by the use of the Parallel Query option. Using Oracle data file striping also helps the performance of your batch processing system.

Hardware and software disk arrays have the added benefit of optional fault tolerance. As described in Chapter 15, “Disk Arrays,” each of the fault-tolerant RAID levels has its advantages and disadvantages. You should first choose the correct fault tolerance for your needs and then make sure that you have sufficient I/O capabilities to achieve the required performance level. If you use fault tolerance, you will most likely have to increase the number of disk drives in your system.

Another benefit of hardware disk arrays is caching. Most disk arrays on the market today offer some type of write or read/write cache on the controller. The effect of this cache is to improve the speed of writing to the disk; the cache also masks the overhead associated with fault tolerance. If your queries often perform table scans, you may see good improved performance with disk controllers that take advantage of read-ahead features.

Read-ahead occurs when the controller detects a sequential access and reads an entire track (or some other large amount of data) and caches the additional data in anticipation of a request from the OS. Unlike an OLTP system in which this is just wasted overhead, in the batch processing system, it is likely that you will need that data soon; if you do, it will be available very quickly.


CAUTION:  It is important to make sure that any controller you use with a write cache is protected against a power failure. Some di sk array controllers on the market today (such as the Compaq disk array controllers) offer a battery-backed, mirrored memory cache that protects your data. Remember: Once Oracle believes that data has been written to the drive, that data had better be there.

Enhancements to the I/O subsystem almost always help in a batch processing environment (as they do with all RDBMS environments). Be sure that you have a sufficient number of disk drives, properly configured. An I/O bottleneck is usually difficult to work around. As with all types of systems, a well-tuned application is very important.

Network Enhancements

Network performance is never an issue during the actual transaction processing phase of the batch job, but it can be an issue during the load and unload phases of the batch job. Because large amounts of data may be transferred across the wire during these times, a high-speed link is beneficial.

You may be able to take advantage of the new 100Base-T technology or you may benefit from a fiber-optics link. The faster the network link, the faster the load/unload happens. You may find it beneficial to install a private link between the batch processing system and the location from which you are loading your data. Try to use the latest technology—such as 100 megabit Ethernet—to provide for future expansion.

Miscellaneous Enhancements

You may be able to take advantage of other hardware or software enhancements to improve the performance of your batch processing system:

  High-speed tape. If you load from tape or unload to tape, you may be able to take advantage of new technology such as DLT tapes or new high-speed tape devices. By enhancing the load/unload phase, the time to run the entire batch job is decreased because loading and unloading is all part of the batch job.
  High-speed compression. If part of your load/unload process requires compressing, moving to the latest hardware/software compression scheme can cut down on the time it takes to perform this compression.

Other miscellaneous enhancements may be available. See what is available on the market and determine whether it can help you.

Summary of System Enhancements

By taking advantage of some of the performance enhancement features available, you may see significant performance improvement. I have worked with the Oracle Parallel Query option and am very impressed with the performance gains you can achieve. Only you can determine how well your transactions can be parallelized.

Using the Parallel Query option in conjunction with a disk array is quite beneficial to your system’s performance. By combining these enhancements with other tuning options such as a large block size and multiblock reads, you are on your way to having a well-tuned batch processing system.

Performance Verification

To verify that the changes you have made have positively affected performance, you must develop some sort of test plan. This test plan should be made up of queries very similar to—if not exactly the same as—the transactions you use on a daily basis. The closer your tests are to the actual transactions, the more accurate the performance verification is.

A good documented test plan allows you not only to verify system performance but to try new things, such as the Parallel Query option, direct write sorts, or some other new feature you may want to implement in the future. The following sections look at what should be tested in the RDBMS and the operating system.


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