Windows 2003 Enterprise R2 32-Bit Memory Limits

Posted on 2010-01-06
Medium Priority
Last Modified: 2012-05-08
Some references state that with the PAE switch Win 2003 R2 Enterprise can support 32 GB of memory even in 32-bit mode.

I wanted to verify if that is true. Also if that is, if installing applications within Windows can take advantage of the 16 GB of RAM I wanted to throw into it (for example SQL)
Question by:RTM2007

Assisted Solution

Vaidas911 earned 164 total points
ID: 26195312
PAE switch, boot.ini /3GB switch are used to take advantage of more than 2GB ram for one application (32bit addressing limit). Enterprise server will support your ram, it has it's own architecture, but you will have to use switches to overide limitation that one application could use more ram. PAE and /3GB switches do realy work, I have client with 2003 Enterprise server and using 9GB RAM just for SQL 2000 (it used only 2GB without switches)
LVL 31

Expert Comment

by:Henrik Johansson
ID: 26195354
Windows Server 2003 R2 Enterprise Edition supports 64GB in 32-bit

See link for supported memory limits

Expert Comment

ID: 26195400
Windows will support lots of RAM, but one application will not be able to use it all without boot.ini and SQL switches.
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Expert Comment

ID: 26195404
Here is an example of the edited line from a boot.ini file on a 2003 ENT server.  

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect /PAE

I use this in my own environment to update RAM past the 4 GB limit.  According to the microsoft link below, you will be limited to 64 GB of RAM in the 32bit ENT version.  To double that you hav eto move to Datacenter version.


Author Comment

ID: 26195420
So would I need to enter the

/3Gb /PAE

switches on the boot.ini? Both or just one?

Then Henjoh09 is saying I can do it without the switches??

Accepted Solution

Sacrificial_Lamb earned 168 total points
ID: 26195606
You only need to add the /PAE switch to support more than 4 GB of RAM.  As for the /3GB switch, I've never used this and the KB article I reference below explains when and why you would use it.  If you were thinking of adding the /3GB switch simply because you wanted to use more than 4 GB of RAM, than the /PAE switch is all you need.  

When you put a /3GB switch into the Boot.ini file of the operating system, you reallocate the virtual address space distribution to give User mode programs 3 GB of space and limit the kernel to 1 GB. The /3GB switch is only required on computers that contain mailbox stores or public folder stores. This switch is not recommended on computers that do not have mailbox stores or public folder stores.
LVL 10

Assisted Solution

LMiller7 earned 168 total points
ID: 26195641
Windows 2003 Enterprise 32 bit will support up to 64GB of RAM if PAE is enabled.

Each process will have a 2GB virtual address space by default. You can increase this to 3GB by using the /3GB switch. Only applications that are large address space aware will benefit from this. This setting has some serious limitations and should not be used without understanding them. There are many misconceptions about this. The system address space will be restricted to 1GB and this has some serious implications. One being that you can use no more than 16GB of RAM, and many cases less.

Read these articles for more information:


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