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Oracle9i Dynamic Reconfiguration Assistant for Windows Server 2003
WARNING:
This is an unsupported software. Oracle will accept no
liability for problems arising from its use, nor does Oracle warrant its fitness
for any purpose. Its use is purely discretionary at the sole risk of the user!!
Introduction
The purpose of this software is to assist an Oracle DBA in dynamically configuring the buffer cache size of instances running on a Windows Server 2003 system with dynamically reconfigurable RAM. On supported hardware, Windows Server 2003 allows memory to be added to a machine without requiring a system reboot. Once the OS detects that additional memory has been added to the system, it is initialized and made available to the applications running on the machine. Using this feature along with
Oracle9i dynamic SGA sizing capability, hardware capacity upgrades can be made in a transparent fashion without causing any downtime.
Oracle9i allows users to dynamically adjust the SGA size by changing the values of parameters such as
DB_CACHE_SIZE, SHARED_POOL_SIZE, and LARGE_POOL_SIZE. However, when there are multiple instances running on a system, making these adjustments manually can be tedious. This utility automates the task of making such adjustments and distributes the added memory among various instances running on the system in accordance to an administrator-specified policy.
Installation and Configuration
Download the ZIP
file containing the following files:
readme.txt : This file
oradimdr.exe : Oracle DR Assistant executable
oradimdr.dll : Additional library
To install, follow these steps:
1. Oracle instances can only be dynamically resized up to the maximum specified by the parameter SGA_MAX_SIZE. For each instance that you would like resized dynamically, adjust their SGA_MAX_SIZE startup parameter to some large value that you don't expect it to exceed. Since SGA_MAX_SIZE itself is not dynamically adjustable, if you change this
parameter you must restart the instance. Note also that dynamic resizing is not supported with VLM.
This tool uses NTS to authenticate with the instances, so make sure that NTS authentication is enabled in each instance and that you are installing this tool as a user in the ORA_DBA group.
2. Make sure your ORACLE_HOME environment variable is set to your Oracle home directory. If there are multiple Oracle homes on the system, pick any one among those with the highest version number. For example, if you have two 9.0.1 Oracle homes and two 9.2 Oracle homes, pick any one of the 9.2 Oracle homes.
To see what your ORACLE_HOME environment variable is set to:
> echo %ORACLE_HOME%
To set it to a new value:
> set ORACLE_HOME=c:\oracle
3. Copy the files oradimdr.exe and oradimdr.dll to the your Oracle bin directory:
> copy oradimdr.* %ORACLE_HOME%\bin
4. Run oradimdr.exe:
> %ORACLE_HOME%\bin\oradimdr
5. The Oracle DR Assistant tool will scan your system for installed Oracle instances, and pop up a wizard to guide you in configuring the tool.
There are two operating modes for the assistant:
- Auto Configuration: Set up the memory allocation policy now, and when memory is hot-added to the system the tool will automatically resize the running instances according to the policy.
- Pop-up Configuration: Defer setting up the memory allocation policy until later. When memory is hot-added to the system, the tool will pop up a window at that time to inform you about the new memory and allow you to choose how to allocate that memory.
If you select "Pop-up Configuration", the wizard will finish and install itself in the system tray.
If you select "Auto Configuration" then the next screen will allow you to set up the memory allocation policy. There are three policies to choose from:
- Fixed: Memory is allocated to each instance according to fixed percentage values that are assigned to them.
- Proportional: Memory is allocated to each instance in such a way that they grow in proportion to their original SGA
sizes.
- Equal: Memory is divided equally among the instances.
Note that the memory will be allocated to the instances' buffer cache by incrementing the DB_CACHE_SIZE parameter. This parameter is typically used to increase performance by reducing the I/O.
The field "Percentage of memory to use" lets you decide what percent of the hot-added memory will be used for resizing SGAs. Typically, you want to leave some of the additional memory unallocated so that it can be available for such things as private memory or other applications. The default of 75% is a reasonable value and can be adjusted to suit your scenario. For example, suppose your system had 2 GB of memory and you hot-added an additional 4 GB of memory to the system. With the default 75% setting, 3 GB out of that 4 GB new memory would be distributed among the instances.
The table below lists all the instances that were installed on the system and their specific policy settings. For each instance, you can enable or disable their participation in the DR resizing operation by clicking on the check box "Enable DR". For the "Fixed" policy, there is an additional field "Resize percentage" that lets you specify what percentage of the memory used for resizing SGAs should go to this instance. For example, suppose you had two instances with SIDs "instance1" and "instance2" and you set their resize percentages to 33% and 67%, respectively. Then, continuing the scenario in the previous paragraph, of the 3 GB to be distributed among instances, approximately 1 GB would be allocated to instance1 and the other 2 GB would be allocated to instance2.
Once you are done setting up the policy, click the "Next" button and the wizard will finish, installing itself in the system tray.
Note that this installation step also will also install the tool in the system start-up. Since the policy settings are stored in
the registry, this means that the DBA does not need to do anything additional to restore the operation of the tool after a system restart.
6. If at any time you would like to reconfigure the tool, simply run the executable again, whether or not it is already running in the system tray:
> %ORACLE_HOME%\bin\oradimdr
Using Dynamic Reconfiguration Assistant while Dynamically Adding Memory
To use the tool to resize your Oracle instances, follow these steps:
1. Add the memory to the system. Consult your system's operator guide for this.
2. If you configured the Oracle DR Assistant tool for "Auto Configuration", then as soon as the operating system detects and initializes the new memory, the tool will begin resizing the instances according to the specified policy. You're done!
3. If you configured the tool for "Pop-up Configuration", then a wizard dialog box will pop up to notify you that it has detected additional memory. The next window will allow you to specify how this memory will be allocated. This process is very similar to the policy set up for "Auto Configuration" described above in step 4. One difference is that it only shows instances that are currently running. Another difference is that you can see what the effect will be on each instances' SGA before committing the change, via the "oldSGA" and "newSGA" columns. Once you have completed the configuration,
click the "Next" button and the resizing will take place. A summary screen will inform you of the results of the operation.
Software
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References
For more information about Dynamic SGA and control of the SGA's use of memory refer to Oracle Administrator's Guide or Oracle Concepts
Manual.
Oracle Corporation, May 2003
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