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3 Replies Latest reply: May 1, 2012 7:38 PM by Aman.... RSS

Oracle Automatic Memory Management

sbing52 Newbie
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Are there any restrictions or best practices regarding the setting of Oracle Automatic and Manual Memory Management (in particular the setting of these parameters: SGA_TARGET, SGA_MAX_SIZE, MEMORY_TARGET, MEMORY_MAX_TARGET) on various Oracle instances on the same server/node/virtual machine. In other words can the memory management schemes be mixed among various Oracle instances on the same server/node/virtual machine. For example suppose a server houses three Oracle instances - inst01, inst02, inst03. Can inst01 and inst03 use automatic memory management and inst02 use manual memory management. Are there any restrictions or best practices that should be noted? If there are multiple Oracle instances on the same server, is it a requirement that they all follow the same memory management scheme or is it a best practice to do so? Obviously, the total memory requested for the Oracle instances combined would not exceed the total physical memory available on the server.

Note: we are currently using Oracle 11g R2 specifically 11.2.0.1 on Solaris
  • 1. Re: Oracle Automatic Memory Management
    sb92075 Guru
    Currently Being Moderated
    sbing52 wrote:
    Are there any restrictions or best practices regarding the setting of Oracle Automatic and Manual Memory Management (in particular the setting of these parameters: SGA_TARGET, SGA_MAX_SIZE, MEMORY_TARGET, MEMORY_MAX_TARGET) on various Oracle instances on the same server/node/virtual machine. In other words can the memory management schemes be mixed among various Oracle instances on the same server/node/virtual machine. For example suppose a server houses three Oracle instances - inst01, inst02, inst03. Can inst01 and inst03 use automatic memory management and inst02 use manual memory management. Are there any restrictions or best practices that should be noted? If there are multiple Oracle instances on the same server, is it a requirement that they all follow the same memory management scheme or is it a best practice to do so? Obviously, the total memory requested for the Oracle instances combined would not exceed the total physical memory available on the server.

    Note: we are currently using Oracle 11g R2 specifically 11.2.0.1 on Solaris
    Each instance operates independently of any other instance.

    The sum total of all SGA sizes can exceed total RAM; but response time performance may suffer.
  • 2. Re: Oracle Automatic Memory Management
    karan Pro
    Currently Being Moderated
    YES you can have different initialization parameter settings for different instances...

    Regards
    Karan
  • 3. Re: Oracle Automatic Memory Management
    Aman.... Oracle ACE
    Currently Being Moderated
    sbing52 wrote:
    Are there any restrictions or best practices regarding the setting of Oracle Automatic and Manual Memory Management (in particular the setting of these parameters: SGA_TARGET, SGA_MAX_SIZE, MEMORY_TARGET, MEMORY_MAX_TARGET) on various Oracle instances on the same server/node/virtual machine.
    Not really or at least I am not aware of.
    In other words can the memory management schemes be mixed among various Oracle instances on the same server/node/virtual machine.
    Each instance is going to work individually so the answer is yes .
    For example suppose a server houses three Oracle instances - inst01, inst02, inst03. Can inst01 and inst03 use automatic memory management and inst02 use manual memory management.
    Yes.
    Are there any restrictions or best practices that should be noted? If there are multiple Oracle instances on the same server, is it a requirement that they all follow the same memory management scheme or is it a best practice to do so?
    As I said, not that I am aware of. As long as you are able to accommodate the memory requirements under your installed RAM, you should be okay.
    Obviously, the total memory requested for the Oracle instances combined would not exceed the total physical memory available on the server.
    Yep.
    Note: we are currently using Oracle 11g R2 specifically 11.2.0.1 on Solaris
    Patch to the latest patchset which is 11203.

    Aman....

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