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Dynamic Reconfiguration and Oracle 9i Dynamically Resizeable SGA

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This article explains how Oracle 9i can operate in combination with Sun's dynamic reconfiguration (DR). It provides a brief overview of DR, intimate shared memory (ISM), dynamic intimate shared memory (DISM), and dynamically resizable system global area (SGA), and explains how these technologies fit together. In addition, this article provides step-by-step details for configuring Oracle relational databases on Sun Fire servers so that the DR capabilities of the Sun platform can be maximized. This article requires an intermediate reader. The features described in this article should be used with the Solaris 9 OS Update 2 and newer.
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UNIX® has established its place in the data center, supporting the most mission-critical processes in any enterprise. Sun Microsystems has played a significant and pioneering role in this evolution by introducing support for server partitioning, on-line hardware servicing, and online partition resizing.

The SolarisTM 8 Operating Environment (SolarisTM 8 OE) and higher includes enhanced software support for these dynamic platform capabilities. Today, many major software vendors use this software in their products.

This Sun BluePrintsTM OnLine article explains how Oracle 9i can operate in combination with Sun's dynamic reconfiguration (DR). It provides a brief overview of DR, intimate shared memory (ISM), dynamic intimate shared memory (DISM), and dynamically resizable system global area (SGA), and explains how these technologies fit together. In addition, this article provides step-by-step details for configuring Oracle relational databases on Sun FireTM servers so that the DR capabilities of the Sun platform can maximized.

This article presents the following topics:

  • "Dynamically Reconfiguring UNIX Systems"

  • "Using Dynamic Reconfiguration on Sun Fire Servers"

  • "Dynamic Intimate Shared Memory"

  • "Dynamically Resizing the SGA in Oracle 9i"

  • "Configuration Example"

Dynamically Reconfiguring UNIX Systems

Dynamic reconfiguration is the capability to remove from or add system resources (for example, CPUs, memory, and I/O cards) to a system without having to halt the operating system or the applications running on it. This feature was first introduced in 1997, and it is one of the factors that has contributed to Sun's success in the mission-critical arena.

In recent years, all major UNIX vendors have developed similar functionality. For example, IBM developed lpars for use on their p-series servers, and HP developed npars and vpars for use on the SuperDome.

In this article, we do not provide a detailed comparison of all UNIX server partitioning technologies that are available in the market today. Instead, we highlight two distinct advantages of Sun's server partitioning technology. (Note that on a Sun server, a partition is referred to as a domain.)

  • First, Sun's server partitioning technology is based on the hardware modularity of the Sun Fire servers and it guarantees the highest possible isolation between domains. Because the failure of a component in a module (for example, the failure of CPU, a memory board, or an I/O board) has been proven to impact only the domain that is using the module, other domains are unaffected by the failure. They stay up and are in no way aware of the fault.

  • Second, the technology is mature. While dynamic reconfiguration is a technology that can now be used in a production environment, it took several releases of the Solaris Operating System (Solaris OS) to reach this level of reliability. Companies that are just now announcing dynamic partitioning will lack this experience.

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