Re: Maximum number of Oracle instances on Windows

I usually find memory constraints the most challenging when configuring databases on Windows. Per-process memory should not be a problem unless the /LARGEADDRESSAWARE <http://go.microsoft.com/FWLink/p/?LinkID=132948> option is cleared, in which case an instance cannot use more than 2GB. This is an issue as on Windows, unlike Unix, all Oracle processes run as threads in the same memory space (including client server processes).

If you want to load all SGAs into memory at the same time, you should also pay attention to the different Windows versions, as the supported amount of physical memory is limited on various editions, e.g. 32GB for the 2008R2 standard edition.

You can find the per-process memory and physical memory limits at: http://msdn.microsoft.com/en-us/library/windows/desktop/aa366778%28v=vs.85%29.aspx#memory_limits and http://msdn.microsoft.com/en-us/library/windows/desktop/aa366778%28v=vs.85%29.aspx#physical_memory_limits_windows_server_2008_r2

Cheers,
Tony

On 20/09/14 05:38, Schauss, Peter (ESS) wrote:
> One of the sites that I support has asked me to spec out new production and dev/qa database servers. They are currently running Windows. On the production server they expect to have 15 or 16 small Oracle instances with a total SGA+PGA of 35 gb. About half of their instances are at 11.1 but they well be eventually upgrading all of them to 11.2. If we go with Windows for the new servers we will be running Windows Server 2008r2 64 bit.
>
> I would, obviously like to move them to Linux, but I expect that they will resist the idea. Are we going to run into any absolute or practical limits running 15 or 16 Oracle instances with 35 gb of memory on a Windows server?
>
> Thanks,
> Peter Schauss
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