A Note on Worked Examples

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When we began to put this book together, we took a look at the breadth of topics involved and, after much hand-wringing, made a touch decision: all examples that we will work for this book have been done on Linux.

We understand that, more likely than not, your production system may not be on Linux, and some of the configuration for high availability include OS-specific steps, particularly when it comes to using RAC with a third-party clusterware product.

A couple of things guided our thinking: first, we are emphasizing a database-centric view of availability, and the strong majority of the technology we discuss in this book act identical on all operating systems. So the code is portable, and is not affected by our test environment.

Second, many of the aspects of an OS-specific configuration can be eliminated through usage of Oracle-provided add-ons: Oracle Cluster File System for RAC, Automated Storage Management for volume management, and RMAN for media backups.

Third, we wanted to write a book that you can take into a small testing environment, that has been configured on the cheap to do proof-of-concept on some of the availability techniques in this book. For such environments, it only makes sense to use a cost-sensitive OS such as Linux, running on commodity-priced hardware. It also means that you can teach yourself how to use complex enterprise-computing concepts in the basement of your own home. Being self-taught DBAs ourselves, we understand the value of tinkering for comprehension.

Finally, Linux is emerging as an operating system that large enterprises are taking seriously as the strategic platform of the future. This includes Oracle Corporation, which sees low-priced operating systems and commodity-priced hardware as the key that will unlock the potential of grid computing and make high availability a reality for all databases.

A Note, Then, on Linux Versions

Oracle Database 10g does not work on all versions of Linux. While this seems unfortunate at first glance, the reality is such that the Linux kernel has a high degree of volatility due to its open source nature. To avoid unsupportable kernel upgrades, Oracle worked with the major Linux distribution providers to get an Enterprise Linux developed that can be guaranteed to work with Oracle Database 10g.

Oracle is perhaps most cozy with Red Hat, which has two products that Oracle Database 10g is supported on: Red Hat Advanced Server 2.1 and Red Hat Enterprise Linux 3.0. In fact, if you have a registered copy of these operating systems and a licensed copy of Oracle, you can get OS support for the Red Hat product from Oracle.

Oracle is also supported on UnitedLinux 1.0, an enterprise-ready Linux that comes from a collaboration between SuSe, Turbo, and other distributors. However, Oracle does not provide OS support for United Linux.

We worked our examples on Red Hat Enterprise Linux 3.0. While it costs a bit more to purchase even the low-end RHEL, we recommend it. While you may be able to get Oracle to work on non-supported distributions, it will take more work, and you will be laboring alone.

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