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memory windows

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Michael O'brien_1
Regular Advisor

memory windows

Hi,

I have an N-Class with 6gb of RAM. The are 12 oracle instances running on this box. Only six of these instances have been entered in the /etc/services.window . I'm assuning that the other instances have been over look and the /etc/services.window file hasn't been updated when the new instances where add to the machine.

Or does the amount of RAM affect the number of entries you can place in your /etc/services.window, ie if you have 6GB of Physical RAM then you can only have six entries in the /etc/services.window file?
The max_mem_window is set for 20. So I guess I could have 20 instances running?

What is the effect of running some instances not configured to use memory windows, other than there being a 1.75GB limit. How does the 1.75GB limit related to entries in the /etc/services.window file.

This machine also runs oracle apps server and oracle express, should I put these into the /etc/services.window.

Thanks
Michael
3 REPLIES
Stefan Farrelly
Honored Contributor
Solution

Re: memory windows


Each entry in the services.window file is a 1 GB memory window (quadrant). With 6 GB of RAM on your box you can only have a maximum of 6x 1 GB memory windows, hence the 6 entries you have in your file. You cant have any more. I doubt you could be using all 6 anyway as some of your 6 GB of RAM is needed for the OS and other processes.

max_mem_window=20 means 20 entries in the services.window file. Seeing as you can only have 6 this seems high, but I doubt its anything to worry about.

Anything not using memory windows (application written to utilise them) is limited to 1.75 GB of memory (if a 32 bit app - 64bit apps can of course use > 6 GB).

I dont think you should add anything to your services.window file, it should have individual entries for each instance. See manpage on services.window
Im from Palmerston North, New Zealand, but somehow ended up in London...
Santosh Nair_1
Honored Contributor

Re: memory windows

Michael,

There is an excellent doc in /usr/share/doc called mem_wndws.txt, which explains all about memory windows.

A quick glance at the doc says that if you have max_mem_window set to 20, then there are a total of 21 memory windows (one default one). The /etc/services.window file is used to list the private keys for each memory window. I don't believe there is a correlation between the number of entries here and the amount of memory. These entries are used to group applications to the shared resource.

Also consider that if you didn't set up a memory window, then you could create a shared resource of up to 1.75 GB, so on a 6 GB system, if you have 12 databases running, unless you are creating some really large shared memory segments, i.e. more the 1.75 GB, then you would quickly run out of memory.

-Santosh
Life is what's happening while you're busy making other plans
Michael O'brien_1
Regular Advisor

Re: memory windows

Stefan,

As I have 6 other instances as well as the 6 referenced in the /etc/service.window file, a total of 12 in total as well as various other apps running. How is the memory distributed? Are the six in the /etc/service.window file taking away the memory resource of the other instances and apps.

Would I get better to remove some of the instances from the/etc/service.window file

Thanks
Michael