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NPP and Paged Pool memory query

Hi

Our environment is Windows 2003/2008 servers.

From reading around, my understanding of memory is:

Non-paged Pool Pool (NPP) memory is memory reserved by the operating system kernel that cannot be paged to disk.  It is used for critical system buffers that must always be accessible at all times

Hence the reason NPP is used by drivers etc.

Does this mean that Paged Pool memory is 'normal' memory that CAN be paged to disk? And it's used by both the OS and applications on the server, or just one or the other?

Finally, I understand that the /3GB switch changed the proportion of virtual memory reserved for the OS from 2GB to 1GB. How does this affect NPP and Paged Pool memory? Does the PAE switch also affect NPP/Paged Pool memory?
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kam_uk
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kam_uk
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1 Solution
 
NeuromCommented:
Kernel mode components can choose between paged- and nonpaged pool memory pool, depends on there needs.

User mode applications use always the paged pool, except they lock memory to keep them resident.

Paged memory can be paged out, this means that your hard drive will be used as memory.
Nonpaged pool memory can't be paged out.

/3GB and /PAE limits both paged and non-paged pools very significantly.

For more information, please red: http://blogs.technet.com/b/askperf/archive/2007/03/07/memory-management-understanding-pool-resources.aspx

Hope this help
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kam_ukAuthor Commented:
Thanks Neurom.

Good link - but could you expand on how /3Gb and PAE affects paged/npp memory? The link doesn't mention it.
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NeuromCommented:
How, depends on many factors. What is changed is the space reserved for these two "types" of memory; paged & nonpaged.

For more information, if you want you can see the following links:

http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm
http://blogs.technet.com/b/askperf/archive/2007/03/23/memory-management-demystifying-3gb.aspx
http://blogs.technet.com/b/askperf/archive/2007/02/23/memory-management-101.aspx
http://blogs.technet.com/b/markrussinovich/archive/2009/03/26/3211216.aspx

Hope this can help you to understand,
Bye
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