• IBM Consulting

    DBA Consulting can help you with IBM BI and Web related work. Also IBM Linux is our portfolio.

  • Oracle Consulting

    For Oracle related consulting and Database work and support and Migration call DBA Consulting.

  • Novell/RedHat Consulting

    For all Novell Suse Linux and SAP on Suse Linux questions releated to OS and BI solutions. And offcourse also for the great RedHat products like RedHat Enterprise Server and JBoss middelware and BI on RedHat.

  • Microsoft Consulting

    For Microsoft Server 2012 onwards, Microsoft Client Windows 7 and higher, Microsoft Cloud Services (Azure,Office 365, etc.) related consulting services.

  • Citrix Consulting

    Citrix VDI in a box, Desktop Vertualizations and Citrix Netscaler security.

  • Web Development

    Web Development (Static Websites, CMS Websites (Drupal 7/8, WordPress, Joomla, Responsive Websites and Adaptive Websites).

23 December 2010

Seasons whishes

22 November 2010

Windows4all has become SilveOS.com

The Windows4all project is now closed and has become the silveos.com. Another step in cloud computing. Here are some of the windows of silveos.com in action:

Here is an example shown of the opening page. It looks already very mature and sofar it works mature as well, with the latest IE9 Browser on the desktop.

Here is the IE9 browser in action. This means Computing power that is cheap accessible and secure for everyone. 

There is already a frequent asked question section on the silveos.com site available. DBA Consulting is as a registered partner in the process of becoming a Official Microsoft BPOS reseller, with all the cloud offerings at Microsoft value for money cheap deals. 

Soon you will here more about he Microsoft Cloud Offerings.

(DBA Consulting is working also on Cloud Offerings from competitive vendors like Oracle's Enterprise Clouds (elastic) and Google Apps Cloud Offerings. This will involve alternative or totally different Cloud Computing solutions)

05 November 2010

The Oracle Unbreakable Linux Network

The Oracle Unbreakable Linux Network’s web portal is located at http://linux.oracle.com.

Note: Before you can access the Oracle Unbreakable Linux Network it's necessary to create an Oracle Single Signon account. Your existing My Oracle Support (MOS) Oracle Single Signon account will not work with the Oracle Unbreakable Linux Network until the account has been registered with the Oracle Unbreakable Linux Network. Click the Register link at the the Oracle Unbreakable Linux Network portal to a) create a new Oracle Single Signon account or to b) associate your existing Oracle Single Signon account with the Oracle Unbreakable Linux Network. 

Figure 1:  Highlights the Oracle Unbreakable Linux Network web portal.

Figure2  shows an Oracle VM server being updated from the Oracle Unbreakable Linux Network using the up2date program.

The second option is to update Oracle VM servers using a local yum repository. A local yum repository can be hosted on any Enterprise Linux system that has been registered with the Unbreakable Linux Network with internet access and Apache. Local yum repositories are populated and synchronized with RPMs that are hosted at the Unbreakable Linux Network using a script and a local cron job. The up2date program or the yum program can be used with a local yum repository.

Figure 3 shows an Oracle VM server being updated from a local yum repository.

07 October 2010

Official Oracle Unbreakable Linux Reseller!

From now on Oracle Unbreakable Linux support can be ordered through me as an official reseller!

The new Unbreakable Enterprise Kernel is the result of the combined efforts of Oracle's Linux, database, middleware, and hardware engineering teams, and is :

§          Fast—More than 75 percent performance gain demonstrated in OLTP performance tests over a Red Hat Compatible Kernel; 200 percent speedup of Infiniband messaging; 137 percent faster solid state disk access
§          Modern—Provides optimizations for large NUMA servers; improved power management and energy efficiency; fine-grained CPU and memory resource control
§          Reliable—Supports the Data Integrity Extensions and T10 Protection Information Model, to stop corrupt data from being written to storage; hardware fault management improves application uptime; low overhead performance counters for tracing
§          Optimized for Oracle—Built and tested to run Oracle hardware, databases, and middleware with the best Linux performance and reliability available

Price Range

Get industry-leading, global support from Oracle for your Linux operating system implementations, with the Oracle Unbreakable Linux Support Program.
354.3€ - 1,062.91€
Get industry-leading, global support from Oracle for your Linux operating system implementations, with the Oracle Unbreakable Linux Support Program.
851.32€ - 2,553.96€
Get industry-leading, global support from Oracle for your Linux operating system implementations, with the Oracle Unbreakable Linux Support Program.
84.49€ - 253.48€
Get industry-leading, global support from Oracle for your Linux operating system implementations, with the Oracle Unbreakable Linux Support Program.
993.33€ - 2,979.98€
Get industry-leading, global support from Oracle for your Linux operating system implementations, with the Oracle Unbreakable Linux Support Program.
1,632.35€ - 4,897.05€

Oracle Unbreakable Linux in offering from now on!

As of now I am offering Oracle Unbreakable Linux Enterprise Edition Services:

I acquired the following Certifications for this track:

- Oracle Enterprise Linux Pre-Sales Specialist

- Oracle Enterprise Linux Sales Specialist

- Oracle Enterprise Linux 5 Technology Support Specialist

- Oracle Database 11g/R2 Pre-Sales Specialist

- Oracle Database 11g/R2 Sales Specialist

- Oracle Database 11g/R2 Technology Support Specialist

- Oracle Database 11g/R2 Performance Tuning Sales Specialist

- Oracle Database 11g/R2 Performance Tuning Pre-Sales Specialist

- Oracle Database 11g/R2 Performance Tuning Technology Support Specialist

- Oracle OCP 9i, 10g, 11g and Siebel 7.7 and 7.8 Certified Consultant

11 August 2010

How can you improve on this?

Oracle Enterprise Unbreakable Linux Support options

Network Support — Access to patches and updates via Oracle Unbreakable Linux
Network (ULN). This is equivalent to Red Hat’s Basic support, for less than a third of
Red Hat’s price.

Basic Support — Access to patches and updates via ULN, plus 24x7 support and
complete Linux server lifecycle management with Oracle’s Management Pack for
Linux, and Oracle Clusterware. This support is equivalent to the very best support
offered by Red Hat, for far less than what Red Hat charges. The Management Pack
not only delivers functionality unavailable from Red Hat but is also free as opposed
to Red Hat’s RHN modules and satellite server products that are available for a fee.

Premier Support — Access to patches and updates via ULN, 24x7 support, complete
Linux server lifecycle management with Oracle’s Management Pack for Linux,
Oracle Clusterware, backporting, and lifetime support. This support, unavailable
elsewhere, is what Oracle — and its enterprise customers — mean by true enterprise
support. It is the sort of support available to commercial OSes but not previously
available for Linux. Targeted bug fixes and patches are not merely obtainable in the
latest or future versions, they are obtainable for the version the customer is currently
running. This is essential for mission-critical operations impeded by a problem in the
operating system. Lifetime support ensures that, after the standard support cycle,
customers can continue to obtain support and knowledge on their existing
deployments without their having to move to later versions.

10 August 2010

Why Oracle Unbreakable Enterprise Linux on HP? That's why!

Rising operational costs are driving clients to seek higher performance technology solutions at a lower cost," said Scott Farrand, vice president, Infrastructure Software & Blades at HP. "The combination of Red Hat Enterprise Linux 5.5 on energy-efficient HP ProLiant servers and HP BladeSystem with Virtual Connect Flex-10 technology provides clients a high-performance, low-cost platform to run demanding Linux workloads in virtualized environments.

06 August 2010

A small consolation after last nights canceled RAC/SIG Webinar.


After the failed attempt the give a presentation about the following:

Provisioning Oracle RAC in a Virtualized Environment using Oracle Enterprise Manager
Presented by Kai Yu
Oracle Enterprise Manager provides an end-to-end solution for automated provisioning, patching, and lifecycle management of virtual infrastructures and Oracle Real Application Clusters (Oracle RAC). Oracle Enterprise Manager provides a central management solution for Oracle RAC in virtualized environments. Learn how Oracle Enterprise Manager allows rapid provisioning of Oracle RAC systems in a virtualized environment by using prebuilt Oracle VM templates and Oracle RAC provisioning features. Authored by a Dell engineer and the Oracle enterprise manager product manager, this session shows the best practices to establish an Oracle VM environment on commodity servers and to configure the guest VMs for deploying Oracle RAC using Enterprise manager VM management pack. It will focus on how to provision and scale up an Oracle RAC system in no more than a few clicks using the enterprise management provisioning pack. The presentations will share the road map for upcoming provisioning, virtualization, and cloud computing features of Oracle Enterprise Manager.

I think the link to the above with paper from 2006 can be informative to most RAC implementers.


05 August 2010

Comparing Windows 7 to Linux on some points.


From a security point of view I think that Windows 7 scores very well as well:

Forrester Research

recommends that businesses that value quick patches look to Microsoft and Debian. At the same time, though, Forrester is concerned that Microsofts new monthly security policy may delay important fixes.

Read the article:


Why one should choose Oracle Unbreakable Linux Enterprise Edition!

Red Hat Enterprise Linux powers many of the
world 's most demanding financial institutes

"Our ability to add incremental capacity to the thousands
of servers we maintain daily with the reliability to deal
with the great demands of day-to-day trading is only
capable because of Linux and our work with Red Hat."

- Joe Panfil
Managing Director of Enterprise
Technology Services, CME Group


With Red Hat Enterprise Linux, you receive:

The applications you need
Thousands of certified applications from ISVs (Independent Software
Vendors). redhat.com/partners/isv/

Your choice of hardware platform
Hundreds of certified hardware systems and peripherals from leading
OEM (Original Equipment Manufacturer) vendors, spanning multiple
processor architectures. redhat.com/partners/hardwarepartners/

Comprehensive service offerings
Up to 24x7 support with one-hour response, available from Red Hat
and selected ISV and OEM partners. redhat.com/support/

The leading operating system
Excellent performance, security, scalability, and availability,
with audited industry benchmarks. spec.org, tpc.org

Robust and quality technology
Red Hat is the world's leading open source developer, enabling
it to deliver the highest-quality enterprise deployments.

A stable future
Every major version provides stable application interfaces and seven
years of product support.

A product family that enables seamless interoperation of systems from
the laptop, to the datacenter, to the mainframe. Plus, excellent interoperability
with existing UNIX and Microsoft® Windows® deployments.

For reasons of objectivity one can also take a look at the article found at this link:


Because of practical jokers hacking I included the whole article (copy rights LinuxForums.org mind you).

A review of the 10 major Linux distributions out there, giving the pros and cons of each and every one of them


The Microsoft Windows operating system is developed and released by a single company. It comes with a minimal set of applications (a calculator, a few games, some networking tools, an Internet browser.. etc). Other software can be obtained by users from various sources and installed on the operating system.
GNU/Linux is different. A GNU/Linux operating system is made of a Linux kernel, a set of GNU tools, an installation program, a package management system and a lot of other software components. Because all these components are free to use and to distribute, anybody can assemble and configure them according to their needs and create their very own GNU/Linux operating system. Since 1993, a lot of people and companies have been distributing Linux operating systems. These distributions made it easy for people to get and to install a working GNU/Linux system on their personal computer.
At first only a few distributions were available. Nowadays there are so many, that it would be pointless to compare all of them. The website http://www.distrowatch.com lists more than 350 active distributions and reports new releases almost every day. Of course, some distributions are quite similar, although some others are very different to each others. Depending on your needs you'll prefer some more than others.
All distributions include the Linux kernel developed by Linus Torvalds and the GNU tools developed by Richard Stallman but they don't necessarily use their latest versions. Some distributions even make their own changes to the kernel. Distributions usually differ in the choice of software applications they offer, in the way these software applications are configured and in the way they are installed and upgraded. Distributions also differ in many aspects such as their philosophy towards proprietary software, their priorities between ease of use and efficiency or between stability and latest technology. In fact, every distribution is different and this means you have more than 350 ways to run GNU/Linux!
Of course some distributions are more popular than others. This article is dedicated to the 10 most famous and popular: Debian, Slackware, Fedora, Mandriva, Suse, Ubuntu, Knoppix, Gentoo, Mepis and Xandros.


Debian is one of the oldest GNU/Linux distributions. It was created in 1993 by Ian Murdock who named it after the combination of his own name and the one of his then-girlfriend (now wife) Debra. The Debian project is non-commercial and gathers more than a thousand developers throughout the world. A strict organization and clear guidelines made its releases famous for their stability and reliability. The project is very ambitious and supports more than 15,000 packages on 11 architectures: m68k, SPARC, Alpha, PowerPC, x86, IA-64, PA-RISC, MIPS (big and little endian), ARM and S/390. AMD64 is also supported although it is not officially included in the distribution. Debian is known for its strong adherence to the Unix and free software philosophies, its stability and its huge community. It is also very well documented and translated in many languages. Its software package management is extremely powerful and was adopted by many other distributions. Although it is meant to be a general-purpose distribution, the quality of its releases made Debian a distribution of choice for servers.
Debian provides three branches: "Stable" which corresponds to the latest release, "Unstable", which is in perpetual evolution and "Testing" which represents the next release to-be. Although it is possible to use "Testing" and to stay up to date, a lot of people are unhappy with the slow release cycle, which makes the "Stable" branch quickly outdated. For this reason Debian is seen as a serious and stable distribution but not as a cutting-edge and reactive one. This "outdated" reputation combined with the absence of graphical installation or configuration tools made Debian look hard to use and slow to evolve. When it comes to desktop, a lot of people prefer fast release cycle, eye-candy configuration tools, graphical installers and ease of use.. and this is not what Debian is.
Official website: http://www.debian.org
Pros: Open-Source philosophy, non-commercial project, strong community, huge selection of packages and supported architectures, one of the best package management, excellent documentation, extremely stable and well-tested releases, modular, fast.
Cons: Slow release cycle, text-based installer, lack of configuration tools


Founded in 1992 by Patrick Volkerding, Slackware is the oldest surviving GNU/Linux distribution. It is very secure, stable and it is often recommended for server installations. The package management is minimal and doesn't deal with dependencies, the installer and configuration tools are text-based and almost everything is done through configuration files. Slackware doesn't offer graphical frontends nor eye-candy configuration tools. When Patrick was asked why Slackware releases do not have code names, he simply replied that there was no need. In fact the distribution focuses on stability and is well known for being bug-free. System administrators usually say that Slackware is the most Unix-Like GNU/Linux distribution. Most packages are used in their pristine form without any Slackware made improvements. Slackware is usually not recommended to novice users although it is easy to configure and probably one of the most formative distributions. What a user learns while configuring Slackware usually applies to any distribution. Rather than using distribution-specific configuration tools, the user has to modify settings in configuration files and so he has to learn about Linux internals which are common to all distributions. For these reason the Slackware distribution is usually used by system administrators, eager to learn novice users or simply Slackware fans :)
Official website: http://www.slackware.com
Pros: Stability, security, strong adherence to Unix principles, speed and performance.
Cons: Minimal package management, infrequent releases, limited hardware detection.


One of the best known Linux company in the world is Red Hat, founded in 1995 by Bob Young and Marc Ewing. In 2003, Red Hat decided to focus on business and stopped releasing its public distribution. The company chose to sponsor a community driven project called Fedora. Red Hat Linux 9 was the last version in the Red Hat product line and was replaced by Fedora Core. This distribution is quite unique and mixes leading edge features and conservatism. The result is a stable and secure system with frequent releases and up to date packages which suits both server and desktop installations. The package management is based on RPM, invented by Red Hat, and it is enhanced by a set of tools like Yum, which bring additional features similar to the Debian package management. Because of its close relationship with Red Hat this distribution is very popular among companies. Efforts were also made to make it attractive to the public and Fedora is full of graphical configuration and administration tools. The installation is also graphical and special attention was put to the look and feel of the distribution. As a result Fedora is a popular choice for both desktop and servers among Linux users.
Official website: http://fedora.redhat.com
Pros: Widely used, good support, innovation, good-looking desktop, configuration tools.
Cons: Not as stable as Debian or Slackware for server use, not as easy and up to date as Suse or Mandrake for desktop use. Fedora is truly a general-purpose distribution.


Originally called Mandrake and created by Gael Duval in 1998, Mandriva is based on Red Hat. It uses a RPM-based package management, which is enhanced with a tool called urpmi. Mandriva became famous and popular since its first release thanks to an efficient and powerful graphical installer, which is still considered the best nowadays. The default Gnome desktop environment used in Red Hat was replaced in favor of KDE and some good looking configuration tools were added. Also, Mandriva tends to include new versions of software applications as soon as possible and to stay up to date as much as possible, relying on the users to report bugs a posteriori. As a result, Mandriva is highly up-to-date and even though some of its releases are buggy it remains the best distribution for people who are new to Linux or people who find it acceptable to experience some crashes if this means benefiting from the latest versions of applications.
Official website: http://www.mandriva.com
Pros: Highly up-to-date, easy to use, good looking desktop, good community support.
Cons: Unstable, releases are initially reserved to mandrivaClub members and then made public after several weeks.


Since its creation, Suse has always been seen as a distribution of choice for desktop installations. It benefits from a powerful installer and configuration tool called YaST. Professional attention is made to detail, the default KDE desktop environment, the boot process, everything is tailored to make Suse pleasant to the eyes and a serious choice for professional desktops. In 2003, Novell acquired the company and made ISOs of Suse releases freely available on the Internet. Novell also opened the development to public participation and released YaST under the General Public License. Since the launch of OpenSuse, the distribution is now completely free. Suse is stable, polished and pleasant to use. It is probably one of the best desktop solutions.
Official website: http://www.suse.com , http://www.opensuse.org
Pros: Up-to-date, easy to use, good looking, stable.
Cons: Speed and performance.


In 2004 a distribution which was never heard of before, quickly became the most popular and famous of all distributions: Ubuntu. Based on the "Unstable" branch of Debian, Ubuntu features a fast release cycle, up to date and numerous packages, fast download mirrors, great documentation and even free shipment of CDs. Even though the installer is text-based and the configuration tools are not as good looking or integrated as those found in Fedora, Suse or Mandriva, this distribution quickly became the most used for desktop use. Ubuntu was created by Mark Shuttleworth and is distributed by his company Canonical Ltd. It is not clear whether or not Ubuntu is profitable to Canonical Ltd, but according to the multi-millionaire Mark Shuttleworth, this is not the main priority nor purpose of the distribution. Instead, Ubuntu aims to be an innovative and dynamic general purpose distribution which tackles issues that were not addressed by other distributions. Since its creation, Ubuntu has been the most popular GNU/Linux distribution and every single release is better than the previous one.
Official website: http://www.ubuntu.com
Pros: Great community of users and developers, great documentation, up to date packages, fast release cycle.
Cons: The business model doesn't seem to be viable.


Created in 2003 by Klaus Knopper, Knoppix is a live-CD distribution, which means the user can run it directly from the CD without having to install it on the hard drive. Thanks to an efficient compression mechanism, the Knoppix CD features a huge selection of software. Knoppix also provides a great automatic hardware detection, which is far better than those of other distributions. The CD can be used as a recovery or administration tool, as a Linux demonstration, as a hardware test tool or even as a full GNU/Linux desktop distribution since it is possible to install it on the hard drive once booted from the CD. Releases are frequent and packages, based on Debian's "Unstable" branch are quite up-to-date.
Official website: http://www.knoppix.com
Pros: Live-CD, excellent hardware detection, good and up to date package selection.
Cons: Slow if run from the CD.


Created in 2002 by Daniel Robbins, Gentoo comes from the idea of adding the FreeBSD autobuild feature, "ports" into GNU/Linux. Gentoo is a source-distribution, which means that its packages are not binary but source packages. Each package is meant to be compiled on the user's computer in order to get the best performance and speed out of the resulting compiled binary software. Because repositories use source-packages, they are also very quick to get new software releases as soon as they come out. This results in a very fast and highly up-to-date distribution. The package management is also very efficient and easy to use. On the other hand, the installation of the system and of big packages can be very long and tedious, even with a fast processor.
Official website: http://www.gentoo.org
Pros: Highly up-to-date, very fast, good documentation.
Cons: Long and tedious installation, can be unstable.


Created in 2003 by Warren Woodford, Mepis is a mix between Debian "Unstable" and Knoppix. It is a live-CD which, once booted, features a graphical installation program. Users can simply boot on the CD, try the distribution, and if they like it.. run the graphical installation program. Also, the distribution chose a different path regarding the use of proprietary software, arguing that the user's comfort was more important than the adherence to open-source philosophy. By default, Mepis includes NVIDIA drivers, Flash and Java plugins, Java runtime, multimedia codecs, and other non-free software. The hardware automatic detection is very good and even detects some winmodems. In-house configuration utilities are also provided.
Official website: http://www.mepis.com
Pros: Installable Live-CD, pre-configured with latest plugins and codecs.
Cons: Not yet well-established, poor adherence to open-source principles.


In 2001 Xandros acquired Corel Linux. The distribution was based on Debian and aimed at making it easy for novice users to use GNU/Linux. Nowadays Xandros Desktop is the most user-friendly distribution on the market and is recommended to first time Linux users. In its Deluxe edition Xandros Desktop also includes a NTFS resizing tool and a Windows compatibility layer called CrossOver, which makes it possible to run some Windows applications.
Official website: http://www.xandros.com
Pros: Designed for beginners, easy to use, very stable.
Cons: Small package selection, includes proprietary components, only free for personal use.


People often ask "so which distribution is right for me?". The answer is very simple: "It depends!". It depends on your needs, it depends on your experience, on your philosophy or your tastes. It depends on a lot of things, and even if you found the one you preferred among these 10 majors distributions, don't forget that there are about 340 other distributions available, which could potentially suit your needs. If you're ready for the adventure, go and explore. Read reviews, try as many as you can and make your own mind. Otherwise, if you just need something good without the hassle, stick to these 10 major distributions. If you're running a server, consider Debian or Slackware. If you want to install Linux on your home computer for desktop use, consider them all. If you're new to Linux you could try Xandros, Mepis, Suse or Mandriva. Different people have different tastes and this is exactly why GNU/Linux comes in so many flavors...

04 August 2010

Linux hardening tips:

Here are some useful hardening tips for a Linux environment:


They are relevant for Red Hat Linux 5, and that makes them also relevant for Oracle Unbreakable Linux 5.5, which is an adapted Red hat Linux Enterprise Edition.

03 August 2010

Summary of parallel init.oa parameters

Parameter Name
Default Value
Throttles DOP of a statement based on concurrent work load. Can lead to non-deterministic response times
Deprecated, retained for backward compatibility only
Controls MAX DOP used with Auto DOP. CPU means DEFAULT DOP
Size of the buffers used by the parallel server processes to communicate with each other and the QC
In a RAC environment controls if parallel server process will be limited to the node the statement is issued on or not
Used in conjunction with INSTANCE_GROUPS parameter, it restrict parallel query operations to a limited number of instances 
Deprecated, retained for backward compatibility only
Minimum percentage of the requested number of parallel execution processes required for parallel execution
Minimum execution time time a statement should have before AUTO DOP kicks in. Default 10 seconds.
Number of parallel server processes allowed to run before statement queuing kicks in
Number of parallel server processes a CPU can handle during parallel execution

01 July 2010

Oracle 11g R2 the right choice for you

1   +   1   =   3

No, no mistake!!!!

Oracle   +  Sun  =  Performance and Stability

Oracle Software runs best on Oracle hardware!!

19 May 2010

Make your PL/SQL loops EFFICIENT!!!

Make Loops as Efficient as Possible

Because PL/SQL applications are often built around loops, it is important to optimize both the loop itself and the code inside the loop:

•To issue a series of DML statements, replace loop constructs with FORALL statements.

•To loop through a result set and store the values, use the BULK COLLECT clause on the query to bring the query results into memory in one operation (see "Reducing Loop Overhead with Bulk SQL").

•If you must loop through a result set more than once, or issue other queries as you loop through a result set, you can probably enhance the original query to give you exactly the results you want. Some query operators to explore include UNION, INTERSECT, MINUS, and CONNECT BY.

•You can also nest one query inside another (known as a subquery) to do the filtering and sorting in multiple stages. For example, instead of invoking a PL/SQL function in the inner WHERE clause (which might invoke the function once for each row of the table), you can filter the result set to a small set of rows in the inner query, and invoke the function in the outer query.

And last but not least, use the NOLOGING option!

11 May 2010

Total recall

27 April 2010



Never construct a WHERE clause or query using unfiltered data entered by the user; doing so opens you to attack by SQL injection from malicious users. Instead either filter user input to make sure it does not contain SQL code, or use BIND VARIABLES and view criteria in stead of setQuery().

24 April 2010

Your Database is slow, and now…..

When your Database is slow there are a few possible sources to look for the bottleneck(s) in your Database.

1)    The OS is not tuned correctly.

For Linux and UNIX set your semaphores, shared memory realms and shmmax and shmmin parameters and max_nproc parameters.

For windows set the virtual memory parameter correct.

2)   The Database is not tuned correctly.

Set the init.ora parameters correctly and use AMM and ASMM. Size the UNDO tablespace and the undo segments correctly. For RAC determine whether to use a logical standby Database or a Physical standby Database.

3)   The SQL and PL/SQL statements are not tuned well enough.

Use automatic SQL tuning in oracle 10g and 11g. In earlier releases tune the statements with reprogramming and SQL plan management.

Query Optimizer and Execution Plans

When a SQL statement is executed on an Oracle database, the query optimizer determines the most efficient execution plan after considering many factors related to the objects referenced and the conditions specified in the query. This determination is an important step in the processing of any SQL statement and can greatly affect execution time.
During the evaluation process, the query optimizer reviews statistics gathered on the system to determine the best data access path and other considerations. You can override the execution plan of the query optimizer with hints inserted in SQL statement.

4)   In Oracle 11g use Native dynamic SQL or Static SQL depending on your objective. There is an expert presentation on that from Seven Feuerstein on the TOAD website.

5)   Use Native compiling of Java and PL/SQL procedures and packages in Oracle 11g. Oracle proved substantial improvements in performance of up to a 100 percent!

A new option is available from Oracle:

Oracle TimesTen In-Memory Database (TimesTen) is a memory-optimized relational database that empowers applications with the responsiveness and high throughput required by today's real-time enterprises and industries such as telecom, capital markets and defense. Oracle In-Memory Database Cache (IMDB Cache) uses the Oracle TimesTen In-Memory Database as its RDBMS engine. Deployed in the application tier as an embedded database, Oracle TimesTen In-Memory Database operates on databases that fit entirely in physical memory using standard SQL interfaces. High availability for the in-memory database is provided through real-time transactional replication.