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siddharthaparti

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PAE on Windows 2003 Enterprise

Just a quick question for the experts!!!!!!
I have a IBM X366  box with 8GB RAM on it. It's running  Lotus Notes.
The boot.ini file has the following entry..

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /fastdetect /pae /3gb /NoExecute=OptOut

Does this mean that I am throttling the Lotus notes or any other application to use 3GB of memory out of the 8 GB available?

A quick response will really be appreciated.
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oBdA

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Please note, that the PAE switch is for virtual memory not physical memory.  You have 8GB of physical memory, but 32-bit Windows has 4GB virtual address space.  These are two different things.

As oBdA stated, PAE affects how much of the virutal address space is allocated to the "user" and to the kernel.  By default, a virtual address space is split down the middle, 2GB user and 2GB kernel.  By using PAE the "user" space can be increased to as much as 3GB, but no more.

As your task is limited to 4GB of virtual memory, it can't use any more than 4GB of physical memory (RAM).  Assuming you have enough physical memory, which with 8GB of RAM you do.
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siddharthaparti

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Yep guys. I have understood this.
Now if I have 4 Lotus Notes instances and 8GB RAM with the same Boot.ini file then is it correct to deduce that these 4 instances(With the other applications) would be contesting for the 3GB RAM and effectively the extra 4GB would not be utilized.
I don't think you do understand.  PAE does not control RAM it controls how the virtual memory space is split.

RAM = physical memory, not virutal memory.

Each task can use up to 4GB of virtual memory, this has nothing to do with physical memory..   If you use the PAE switch, 3GB will be used by the user program (Lotus Notes in your example) and up to 1GB for things that the OS needs to help the task run.

If you have four instances of Lotus notes running you could in theory have up to 16 GB of virtual memory in use at once, 4  task s with a max of 4GB of virtual memory = 4  task x 4 GB = 16 GB of virtual memory.

If all four instances actually use all 4GB of their virtual memory, then you will have paging as you only have 8GB of physical memory.

Also, boot.ini is for the operating system, not for a task.  You can't have a different boot.ini per task/instance.
hmm interesting....
Thanks guys. I will awarding the points soon.
appreciate your help.
giltjr,
sorry, but you're confusing things. What you're describing are the effects of the */3GB* switch, as described in the 171793 article.
The */PAE* switch enables large memory support (that is, more than 4GB) for the 32bit W2k3, and allows the OS to reduce swapping; check the 283037 article for details.

siddharthaparti,
yes, the complete 8GB will be detected and used and when you're using the /pae switch (as described in KB283037).
basically making more Ph address exts available to applications as above, to reduce swapping out
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Thanks guys. I had an existing ticket with Microsoft and chatted up with those guys as well about this.
giltjr.......:-) I have indeed understood it.

cheers
Sorry about the one confusing post.  Glad to have been able to help.