/3GB /PAE and windows 2000 Advanced Server Memory utilisation

[DJMUK]

We have combined application & database servers (SQL Server) running W2k advanced server.

They have 4GB of RAM, and don't have either of the above switches in the boot.ini file.

We are rather confused in general about how windows utilises memory, and in paticular what impact the above switches have.

Our SQL Server process is capped to only use 1GB of memory, and other applications tend to use about another 1GB combined.

Does windows 2000 advanced by default allow more than 2GB of physical memory to be assigned to application processes?

Thus if memory utilisation is above 2GB (of application processes), does this mean that hard paging will result.

Does anyone have any advice on how we should set these servers up with respect to memory?

Stats from one of our server from task manager:

Physical Memory:
Total 3669496
Available 1072344
System cache 1342476

Commit Charge:
Total 2413416
Limit 6649316
Peak 2599292

Thanks in advance

 

[TechyMcSe2k]

http://www.brianmadden.com/blogs/br...ws-memory-limit-what-does-it-really-mean.aspx

_______________________________________
I hope any help I give leads to great successes.
MCSE, MCSA, MCTS, CCA, VCP, CCNA

 

[DJMUK]

Hi
Thanks for the link. I'm still quite confused however. I've read quite a bit online about PAE and memory mgmt in windows etc, but it's not clear to me.

Question:
In windows 2000 server with 4GB RAM, apparantly 2GB is allocated to applications, and 2GB is allocated to kernel/system.

Does this mean the sum off all paged-in applications cannot exceed 2GB of physical memory or is up to 2GB of physical memory available to each process and the total can exceed 2GB
Thanks

 

[TechyMcSe2k]

The application sum is not allowed more than 2GB unless the /3GB switch is used; which then allows 3GB for apps and 1GB for system


_______________________________________
I hope any help I give leads to great successes.
MCSE, MCSA, MCTS, CCA, VCP, CCNA

 

[CTIGuru]

Presumably, the use of the /PAE switch in the boot.ini file allows an paged-in application sum of more than 2GB in actual memory (providing, of course, the server has such memory installed)?

I have read a number of articles on this on the web, but they are not very clear about the application sum.

Thanks, in advance, for any responses...

 

[CTIGuru]

Any responses to my last post?

I am a colleague of DJMUK's, and we want to fully understand this issue.

Thanks in advance!

 

[TechyMcSe2k]

Using the /3GB in boot.ini will change the partition between the application (apps) memory space and kernel (system) memory space. This switch gives each application 3GB of memory, which in turn only leaves 1GB for the kernel

All PAE does is “trick” the application into thinking it has more space by creating multiple page tables for each application, also, systems booted, with the proper chipset, /PAE can support up to 64GB physical memory

In the 32-bit Windows world, each application has its own “virtual” 4GB memory space.
Each application gets its own 2GB, but all applications have to share the same 2GB kernel space; so /3GB grants each app 3GB of space and then all apps share the 1GB of kernal space.

Reference: Brian Madden
Source: The 4GB Windows Memory Limit: What does it really mean?


_______________________________________
I hope any help I give leads to great successes.
MCSE, MCSA, MCTS, CCA, VCP, CCNA

 

[CTIGuru]

Thanks for the response.

Just to clarify- without the PAE or 3GB switches and with the maximum 4GB of physical memory is installed, if the kernel is occupying, say, 1.5GB, could the remaining 2.5 GB of physical memory be fully allocated to paged-in applications, or is only 2GB of it usable.

I think, from what you have written, that it can all be used, but any single application can only use 2GB maximum of it.

Thanks, in advance, for your response.

 

[TechyMcSe2k]

By default the kernal will own/occupy all 2GB at all times. And all apps will be allocated 2GB - though the app may not be utilizing it all. The app will then share the kernals' 2GB - so logically; if the other apps are not that intensive, then one app could utilize more of the kernal than others (as needed) for intensive needs.


_______________________________________
I hope any help I give leads to great successes.
MCSE, MCSA, MCTS, CCA, VCP, CCNA