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Pagefile Size Windows Vista 64-bit with 8GB RAM

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August 3, 2008 9:50:32 PM

Surprisingly, I just did a search on this topic and nothing came back I'm curious about Pagefile Size for a Vista x64 machine with 8GB RAM. Right now I have it set at the following:

Hard Drive 1 (Western Digital Velociraptor 300GB) - System OS - 500MB (minimum and maximum)
Hard Drive 2 (Western Digital Raptor 150GB) - System Managed (right now it is around 8GB)

Any recommendations on setting the pagefile size for the 150GB Raptor? I've done searches online and read differing suggestions. Is it better to have "System Managed" or to actually set a minimum and maximum on the 2nd Drive?
August 5, 2008 12:25:23 AM

With so much RAM, why do you need a Virtual Cache? It slow! It was for system with very little RAM.

I have Vista x64 and 4GB and I'm using 512MB. Lower than that or none caused my system to crash.

Do like me, start low and increase until system is stable.

Let us know what was the best! :) 
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August 5, 2008 12:47:30 AM

I've read that some programs require use of the pagefile, regardless of how much RAM you have. I guess I'll just leave mine at System Managed.
August 5, 2008 1:36:30 AM

mikeynavy1976 said:
I've read that some programs require use of the pagefile, regardless of how much RAM you have. I guess I'll just leave mine at System Managed.


You hear advice both ways. Some say turn it off or turn it down to minimum size of 512 meg. Some pretty smart people at Zdnet tell me it's better to let Vista manage it because of some specific ways Vista uses the page file. They were short on specifics but sounded fairly convincing.
August 7, 2008 11:01:10 AM

I%u2019ll only tell you what I%u2019ve experienced so far. I%u2019ve been running the same install of Vista 64 on 4 GB ram for the past year with ought a paging file and it%u2019s fine. I use my machine for gaming and photo editing. I%u2019ve never gone up to 4 GB memory usage and I game with everything @ max @ 1920*1200 so it%u2019s u likely you%u2019ll ever use much more ram than that (cept for some video editing, CAD etc). The only problem I%u2019ve had is that Vista will not allow you to use more than 80% of your total memory (RAM plus paging file) so I have had to make a paging file just so I can use all 4GB of my ram and this is only necessary for Crysis. And to clear something up, Vista dose not require a paging file, just because it will populate the paging file when it doesn%u2019t need to does not mean it needs a paging file.

So with 8 GB you have more than enough memory to get away with not having any paging file.


P.S. "They were short on specifics but sounded fairly convincing." I love those non specific but convincing guy's they always know what they're talking about.

P.P.S. Please tell me you got the sarcasm of that...
August 7, 2008 12:26:49 PM

I don't recommend turning the page file off completely - Individual applications may still need to use it occasionally because they have their own address/space limitations, independent of the OS. So even if you have way more memory than you are using, a given app could still need to page something occasionally. If the pagefile is shut off completely and therefore inaccessable, that can cause app crashes.

It's true that with a lot of RAM, you can go a long long time and may even never need it. But just in case: 512MB won't hurt anything, and you've covered all the bases.
August 7, 2008 1:51:34 PM

GeoMan said:
I%u2019ll only tell you what I%u2019ve experienced so far. I%u2019ve been running the same install of Vista 64 on 4 GB ram for the past year with ought a paging file and it%u2019s fine. I use my machine for gaming and photo editing. I%u2019ve never gone up to 4 GB memory usage and I game with everything @ max @ 1920*1200 so it%u2019s u likely you%u2019ll ever use much more ram than that (cept for some video editing, CAD etc). The only problem I%u2019ve had is that Vista will not allow you to use more than 80% of your total memory (RAM plus paging file) so I have had to make a paging file just so I can use all 4GB of my ram and this is only necessary for Crysis. And to clear something up, Vista dose not require a paging file, just because it will populate the paging file when it doesn%u2019t need to does not mean it needs a paging file.

So with 8 GB you have more than enough memory to get away with not having any paging file.


P.S. "They were short on specifics but sounded fairly convincing." I love those non specific but convincing guy's they always know what they're talking about.

P.P.S. Please tell me you got the sarcasm of that...


I hear you. With 8 gig RAM I had mine off for a long time and then I set it to 512 and I didn't have any particular problems - I don't THINK - but then again maybe the few crashes I had were related. It would take a lot of testing to find out. The guy who told me to leave it on was Ed Bott who is a well known Windows guru and author and the guy who wrote the article linked in an above post. This by no means makes it gospel and I still consider this an open question. On this discussion some others said something about xp 64 not needing the page file and many assumed this would be the case with Vista too but that this was not so. Again details were not provided.
August 8, 2008 6:00:17 AM

The only thing that I know of that has to have a pagefile operational in Vista is for memory dumps when it crashes, and who go's back and ever checks those anyway?

I quote from Wikipedia "Paging is usually implemented as a task built into the kernel of the operating system."
August 8, 2008 7:24:30 AM

Wikipedia isn't exactly the most reliable source of information at times...

You found out the hard way, yes Vista doesn't require a pagefile... but some applications do. Turning it off isn't going to give you much noticable increase in performance... and may result in system instability or "out of memory" errors. Yes, Windows obviously slows down a bit when it starts paging to the hard drive, but in the long run it will help performance and not hurt it.

A small pagefile never hurts. I don't know why some people are so opposed to the idea... especially since it helps more than it hinders.
August 8, 2008 7:35:31 AM

A pagefile is never required for an application to run, as long as there is enough free ram. The pagefile is invisible to applications, and they cannot write to it or read from it. The application doesn't know and doesn't care if a specific memory region is backed by physical ram or the pagefile.

You might have an application (like photoshop) that gives a warning, if there is no pagefile, but it is not required to run.

And maybe, just maybe there exist piss poor applications that checks if one is configured, and quits if there isn't. I've haven't seen one, but cannot conclude that they don't exist.

Zoron said:
but in the long run it will help performance and not hurt it.


It can hardly help performance, but it can help if you run out of memory.
August 9, 2008 2:56:44 PM

I've been running Vista 64 with 4GB of ram for a little over a year now with my page file turned off and i've yet to run into any issue. There is no need for it with 4gb of ram let alone 8gb, it just slows you down.

I've never run into an app that wouldn't run because of not having a page file, all the people saying that some apps require it could you please give me an example of an app that you know needs it because i've never, ever ran into one that did.
August 9, 2008 8:42:59 PM

Look up... obviously Crysis does. Turning off the pagefile does NOT help performance. You can argue that it doesn't necessarily improve performance (except for when you need the memory), but I can tell you it does nothing to improve it either. It's better to have one than not to have one.
August 10, 2008 4:06:39 AM

main question; if you dont need page file; then why have it as pagefile could be slower; but some are saying it makes no difference which confuses me...if its not slower, then why not page all memory.

August 10, 2008 4:44:43 AM

The only time a pagefile is "slower" is when Windows it either writing to or reading from it. If you run out of memory and Windows needs to page to the disk, having the pagefile turned off is likely going to crash the app demanding more memory. I'd rather have a temporary slowdown than a crash... but maybe that's just me.

After doing a little more research on MS's site regarding 64-bit... if you have enough RAM installed, you may not need a pagefile. That doesn't mean turning it off will necessarily net you any gains in performance, it just means the file likely won't be used. In that case, a small pagefile still wouldn't hurt, as some apps DO require it. Don't assume that everyone can get by with 64-bit Windows, 4GB of RAM and no pagefile.

Now when you get up 8GB or more, then I'll agree that you might not need a pagefile under most circumstances. However, when 64-bit software that can suck up all that RAM starts appearing... you just may need one again.
August 10, 2008 4:58:35 AM

zoron,

thanks for the information; your posts are usually on the right track and helpful...which i appreciate.
August 10, 2008 10:00:42 PM

Sorry Zoron, Crysis does not require a page file, I play it with no page file. What I’ve done is turn off my page file and then I enable it if I get a low memory warning, if you don’t get the warning ( and you won’t with 8GB of ram) then don’t enable the page file. If you don’t have enough memory (RAM and page file) Vista will just close the program using the most memory, this feature is called Resource Exhaustion Detector and Resolution (RADAR). It will also create an error report which you can read to figure out what happened, so if you try and use too much memory, Vista won’t let you and it'll tell you that, it won’t randomly crash on you.

Programs do not go, I want my memory address to be in the last 512 mb of the 3rd memory stick in your system, just as is isn't compulsory for them to be addressed to the page file.

Mikeynavey1976: what will you be doing with this computer though, if it's just plain office, word and excel stuff and games you will likely never go above 4gb memory usage and you may as well have no page file and never get any slowdowns in Vista. If however you're using CAD, GIS, graphics processing software etc. that do require tones of memory you'll have to have a page file, and probably a large one because many applications like the ones I’ve described above edit some huge files and will require more than 4 or even 8GB ram.

You do not have to have a page file so why have it if it's got the potential to slow you down, UNLESS you use applications that require more ram than you have and then you DO need a page file.
August 10, 2008 10:34:34 PM

Quote:
Mikeynavey1976: what will you be doing with this computer though, if it's just plain office, word and excel stuff and games you will likely never go above 4gb memory usage


FWIW I have 8 and right now over 5 is being used and all I am doing is surfing. It must be superfetch.

What no one has ever explained to me is why the OS will use a pagefile at all if it has yet to run out of ram. Does it use it anyway just because it is there, even if you have 8 gig of RAM? I assume it does use it if it is there as task manager seems to indicate that. And if so is it filling the pagefile with stuff that otherwise would have gone into ram were the page file not there?And if it does fill the page file what are the chances it will actually use it?

I'm not arguing a point here because I don't know the answers to these questions but I would like to see some actual data on this as opposed to hearing a lot of opinions and oft repeated advice which may or may not apply, or maybe applied to XP but not to Vista.
August 10, 2008 10:49:21 PM

It depends on the program. 32-bit programs are limited to a process size of 2GB... so one 32-bit program running all on it's own is never going to consume more than 2GB. Obviously, if one program is near that limit and you only have 4GB of RAM installed... then you're probably going to need a pagefile. If you have 8GB installed, then yeah, chances are you probably won't NEED a pagefile... but of course that depends on what you're running.

Of course, if you don't need the pagefile and you have one anyway, you're not going to experience slowdown in either event. If Windows doesn't need to page anything, it's not going to... so the issue of slowdown becomes moot.

Of course, this applies only to 64-bit versions of Windows when running 32-bit software. Once we start seeing 64-bit software, things just might change a bit. Processes aren't limited to 2GB... instead, they have an 8 terabyte limit. Now I can't imagine any process that would need to eat up that much RAM... but certainly 2 - 4GB wouldn't be totally out of the question. That is unless programmers really start getting sloppy with their code.

Getting back to Crysis though... OK, I didn't make myself clear. Crysis itself doesn't require a pagefile, true. However your experience shows that it is possible to run out of memory when using Crysis with 4GB of RAM. Instead of constantly switching the file on and off... it's better to just leave it on and not have to worry about it. If you had 8GB, then you likely wouldn't need a pagefile at all. So, what I meant to say is that yeah, Crysis doesn't require the pagefile, but if you're running 4GB or less then Windows is probably going to want to page to disk at some point... which, in that case, it makes much more sense to have one than not. Again though, this applies to 64-bit Vista... not 32-bit.
August 11, 2008 7:46:17 AM

Zoron said:
32-bit programs are limited to a process size of 2GB... so one 32-bit program running all on it's own is never going to consume more than 2GB. Obviously, if one program is near that limit and you only have 4GB of RAM installed... then you're probably going to need a pagefile


I'm not 100% clear on what you mean here. If an application has filled out its 2GB user space, a pagefile won't help anything. It won't be able to allocate more memory beyond this point (unsless you reconfigure the layout of the virtual address space). I take for granted you haven't run out of physical ram at this point.

Another point to make. The upper limit of commited memory is physical ram + pagefile. If you let windows manage the pagefile, this limit can be moved. If you make a static pagefile, it cannot. So 1GB RAM+2GB pagefile (static) gives the same amount of memory to commit as 3GB RAM and no pagefile.
August 11, 2008 4:34:49 PM

Hester: the 2GB limit is for any one program, in 32 bit programming a single application may not exceed 2GB memory usage, this is different to the 4GB or whatever that the whole operating system can address to. So let me say that again, a single 32 bit program is limited to 2GB memory usage in Vista/XP 32 bit, but not in 64 bit. This page probably explains better than I do.

As for the upper limit of memory you’re spot on, only thing to add is that Vista may fragment the page file if you let it handle it dynamically, but not if you set it statically yourself.
August 11, 2008 4:53:14 PM

Yes, every program has its own private space (which can be as large as 4GB in 64bit Windows for an 32bit application). But it is not clear to me, if Zoron states that a program can get around this by sending pages out to the pagefile (which it cannot). I have seen this being said in here before
August 11, 2008 10:45:41 PM

No, I did NOT say that. What I did say that if a program is consuming close to 2GB and you have 4GB installed, then you're going to run out of memory. The 32-bit process can't use more than 2GB, but Windows certainly can... and so can any other program running in the background. If one process is taking up half your RAM, then there's a good chance you'll need a pagefile to avoid out of memory errors. I in no way inferred or intended to infer that a 32-bit process could consume more that 2GB of memory.
August 12, 2008 7:31:15 AM



The release of ATI's 4870x2 video card with 2 gigs of ram brings up an interesting issue relating to anyone using 32 bit vista with 4 gigs of ram and using the 4870x2...you might need that page file as your ram will be reduced to 2 gigs under 32 bit vista. In any event, it seems that 64 bit vista is what everyone should be going to...4 gigs total memory just doesnt seem like enough any more.
August 12, 2008 7:35:00 AM

I think I was also triggered by scotteq's comment above :"Individual applications may still need to use it occasionally because they have their own address/space limitations, independent of the OS. So even if you have way more memory than you are using, a given app could still need to page something occasionally. If the pagefile is shut off completely and therefore inaccessable, that can cause app crashes. "

I thought you were backing that statement. If there is lots of free ram, a crash won't be caused by a missing pagefile.
August 12, 2008 4:37:59 PM

dsharp900, you miss the point, the 4 gig limitation is for total memory, that's ram and pagefile together, you could have 4 gig ram and a 500 gig page file, and your system would only be able to address to 4 gig.
August 12, 2008 6:00:56 PM

The pagefile is not a part of that 4GB limitation. You can have as much pagefile space as you want (almost).
August 12, 2008 6:31:37 PM

You can have as big a pagefile as you want, but that still doesn't overcome the 32-bit address limitation. Any 32-bit process is still limited to 2GB, whether it's RAM or pagefile. It can use 1GB RAM and have 1GB paged... but it can never exceed 2GB total memory usage.

Also, 32-bit Windows will never exceed 4GB of address space, no matter how big you make the pagefile. There is no way around that limitation.
August 12, 2008 6:41:19 PM

hester7, you too fail to get the point :) 

Please don't take this personally, rather read this post, have a good laugh, be thankful that you learned something today and have a beer!
August 12, 2008 6:45:35 PM

I failed to get the point? "the 4 gig limitation is for total memory, that's ram and pagefile together" How is that missing the point?
August 12, 2008 6:58:18 PM

You did miss the point. As I've said, you can have an 8GB pagefile with 4GB of RAM, but that makes no difference in the amount of addressable memory in 32-bit Windows. It will never address more that 4GB of total memory and that includes both RAM AND pagefile. The total amount of memory used under 32-bit Windows will NEVER exceed 4GB... RAM and pagefile combined.
August 12, 2008 7:37:33 PM

I'm not talking about the virtual address space. dsharp900 was talking about physical memory. Then GeOMan said: "the 4 gig limitation is for total memory, that's ram and pagefile together". The 4GB physical limitation has nothing to do with the pagefile. You can have several terabytes of pagefile space if you want.

Edit: I missed that you said the same: "will NEVER exceed 4GB". But it will. Each process has its own private virtual address space. Add them all together ...
August 12, 2008 9:01:26 PM


nuf said
August 12, 2008 10:00:31 PM

GeOMan, if you don't have anything more intelligent to say, then don't. The fact is, dsharp9000 was talking about the 4GB limitation (physical) in Windows, and then you guys begin to say that the pagefile is included in this, which is way off. Try and research the subject before calling people noobs.
August 12, 2008 10:08:43 PM

No, memory usage will never exceed 4GB, because that's all 32-bit Windows can address.

http://www.brianmadden.com/content/article/The-4GB-Wind...

Quote:
There seems to be a lot of confusion in the industry about what's commonly called the Windows “4GB memory limit.” When talking about performance tuning and server sizing, people are quick to mention the fact that an application on a 32-bit Windows system can only access 4GB of memory. But what exactly does this mean?

By definition, a 32-bit processor uses 32 bits to refer to the location of each byte of memory. 2^32 = 4.2 billion, which means a memory address that's 32 bits long can only refer to 4.2 billion unique locations (i.e. 4 GB).

In the 32-bit Windows world, each application has its own “virtual” 4GB memory space. (This means that each application functions as if it has a flat 4GB of memory, and the system's memory manager keeps track of memory mapping, which applications are using which memory, page file management, and so on.)

This 4GB space is evenly divided into two parts, with 2GB dedicated for kernel usage, and 2GB left for application usage. Each application gets its own 2GB, but all applications have to share the same 2GB kernel space.

This can cause problems in Terminal Server environments. On Terminal Servers with a lot of users running a lot of applications, quite a bit of information from all the users has to be crammed into the shared 2GB of kernel memory. In fact, this is why no Windows 2000-based Terminal Server can support more than about 200 users—the 2GB of kernel memory gets full—even if the server has 16GB of memory and eight 3GHz processors. This is simply an architectural limitation of 32-bit Windows.

Windows 2003 is a little bit better in that it allows you to more finely tune how the 2GB kernel memory space is used. However, you still can't escape the fact that the thousands of processes from hundreds of users will all have to share the common 2GB kernel space.

Using the /3GB (for Windows 2000) or the /4GT (for Windows 2003) boot.ini switches is even worse in Terminal Server environments because those switches change the partition between the application memory space and kernel memory space. These switches gives each application 3GB of memory, which in turn only leaves 1GB for the kernel—a disaster in Terminal Server environments!

People who are unfamiliar with the real meaning behind the 4GB Windows memory limit often point out that certain versions of Windows (such as Enterprise or Datacenter editions) can actually support more than 4GB of physical memory. However, adding more than 4GB of physical memory to a server still doesn't change the fact that it's a 32-bit processor accessing a 32-bit memory space. Even when more than 4GB of memory is present, each process still has the normal 2GB virtual address space, and the kernel address space is still 2GB, just as on a normal non-PAE system.

However, systems booted /PAE can support up to 64GB physical memory. A 32-bit process can "use" large amounts of memory via AWE (address windowing extension) functions. This means that they must map views of the physical memory they allocate into their 2GB virtual address space. Essentially, they can only use 2GB of memory at a time.

Here are more details about what booting /PAE means from Chapter 7 of the book "Inside Windows 2000," by David Solomon and Mark Russinovich.

All of the Intel x86 family processors since the Pentium Pro include a memory-mapping mode called Physical Address Extension (PAE). With the proper chipset, the PAE mode allows access to up to 64 GB of physical memory. When the x86 executes in PAE mode, the memory management unit (MMU) divides virtual addresses into four fields.

The MMU still implements page directories and page tables, but a third level, the page directory pointer table, exists above them. PAE mode can address more memory than the standard translation mode not because of the extra level of translation but because PDEs and PTEs are 64-bits wide rather than 32-bits. The system represents physical addresses internally with 24 bits, which gives the x86 the ability to support a maximum of 2^(24+12) bytes, or 64 GB, of memory.

As explained in Chapter 2 , there is a special version of the core kernel image (Ntoskrnl.exe) with support for PAE called Ntkrnlpa.exe. (The multiprocessor version is called Ntkrpamp.exe.) To select this PAE-enabled kernel, you must boot with the /PAE switch in Boot.ini.

This special version of the kernel image is installed on all Windows 2000 systems, even Windows 2000 Professional systems with small memory. The reason for this is to facilitate testing. Because the PAE kernel presents 64-bit addresses to device drivers and other system code, booting /PAE even on a small memory system allows a device driver developer to test parts of their drivers with large addresses. The other relevant Boot.ini switch is /NOLOWMEM, which discards memory below 4 GB and relocates device drivers above this range, thus guaranteeing that these drivers will be presented with physical addresses greater than 32 bits.

Only Windows 2000 Advanced Server and Windows 2000 Datacenter Server are required to support more than 4 GB of physical memory. (See Table 2-2.) Using the AWE Win32 functions, 32bit user processes can allocate and control large amounts of physical memory on these systems.


Even if each process has 2GB of virtual address space, they can still only share the 2GB not taken up by the kernel. Virtual address space does not equal pagefile. If it did, you'd have to have one hell of a pagefile regardless of the amount of RAM you had or were able to address.
August 12, 2008 10:24:09 PM

I'm not sure what you don't get.

If we take, lets say 10 processes, each having a 2GB user space. How much pagefile can they potentially use together? Way more than 4GB thats for sure.

No one here has ever said that a single process can address more than 4GB.

And please, for the love of god, differentiate between virtual and physical address space.
August 12, 2008 10:25:57 PM

The point I'm trying to make is that 32-bit Windows cannot address more that 4GB of memory total... PAE does get around that physical limit, but the applications also have to support it and there are no consumer applications that do. Now, when you do have 4GB of RAM installed, some address space is of course going to be consumed by hardware. So typically, you have only 3 or 3.5GB of usuable memory left for the OS. It will use this memory + pagefile to equal 4GB total. Without PAE, it will never exceed 4GB of physical usage... because it can't. Pagefile size is irrelevant... no matter how big it is, 32-bit Windows will never make use of more that 4GB of total memory... including both pagefile and physical RAM. Remember, the pagefile is a substitute for physical RAM when there isn't enough available... but again, 32-bit Windows is limited to 4GB.

August 12, 2008 10:53:45 PM

That is what I keep saying. You have got it all wrong. The pagefile has absolutely nothing to do with how much physical memory Windows can address. And when talking about other devices taking up address space, that is physical address space, not virtual.

Each process can, by default, make use of 2GB virtual memory. Some of that memory might be paged out to the pagefile. Each process can have some of its memory paged out. Add it all up ...
August 12, 2008 11:38:11 PM

To make it a bit more clear why: the pagefile is just a file, it is not memory, so you don't need to address it as memory. When Windows feels like it, it just dumps a portion of a process' virtual address space to the file. It can do this for all processes in the system. Thus, the total amount of paged out data can be enormous.

When the data is needed again, Windows will read the data back into the process' virtual address space, so it can be addressed and executed or whatever.

In non-PAE mode, each pagefile (there can be up to sixteen) can be 4GB. Making a total of 256 GB.
In PAE mode, each pagefile can be up to 16TB. Making a total of 256 TB. Of course, noone will need that much pagefile space, but it is technically possible.
August 13, 2008 2:40:59 AM

From Microsoft Help and Support:

Quote:
How to overcome the 4,095 MB paging file size limit in Windows
View products that this article applies to.
Article ID : 237740
Last Review : October 26, 2007
Revision : 6.7
This article was previously published under Q237740
SUMMARY
When you set the paging file size in Windows, the documentation states that the largest paging file that you can select is 4,095 megabytes (MB). This limit is imposed by the page mapping that we use on x86 processors. These processors cannot handle more pages per page file. This is the limit set per volume; you can actually create paging files this large on one or more drives if you need a larger paging file. If extra drives or volumes are not available, you can create multiple paging files on a single drive by placing them in separate folders.

However, you can create a single page file that is more than 4,095 MB on a Microsoft Windows Server 2003 Service Pack 1 (SP1)-based computer.

Notes To create a larger page file, you must load the Physical Address Extension (PAE) kernel. In Windows Server 2003, PAE is automatically enabled when the server is using Hot Add Memory devices. Alternatively, you can force the PAE kernel by adding the /PAE switch in the Boot.ini file.

To get a complete memory dump from computers that have 4 GB RAM or more, it is still necessary to use the /MAXMEM switch in the Boot.ini file. One of the page files on the system partition must still be 1 MB larger than the amount of RAM installed in the computer to successfully create a memory dump. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
108393 (http://support.microsoft.com/kb/108393/) The /maxmem switch in the Windows Boot.ini file
MORE INFORMATION
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows


Note that reading or writing a paging file of this size can be costly in terms of performance. If you find that you need a paging file of this size, it may be better to add more RAM to the computer. The current algorithm Windows uses to set the default paging file size is:
• If total physical RAM is less than 2 gigabytes (GB), the paging file is set to 1.5 times the amount of RAM or 2 GB, whichever is smaller.
• If total physical RAM is equal to or more than 2 GB, the default size is set to 2 GB.
To create multiple paging files on one volume to overcome the 4,095-MB limit:
1. On the drive or volume you want to hold the paging files, create folders for the number of paging files you want to create on the volume. For example, C:\Pagefile1, C:\Pagefile2, and C:\Pagefile3.
2. Click Start, Click Run, type regedit in the Open box, and then click OK.
3. In the left pane, locate and click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\SessionManager\MemoryManagement
4. Find the Pagingfiles value, and then double-click it to open it.
5. Remove any existing values, and add the following values:
c:\pagefile1\pagefile.sys 3000 4000
c:\pagefile2\pagefile.sys 3000 4000
c:\pagefile3\Pagefile.sys 3000 4000
6. Click OK, and then quit Registry Editor.
7. Restart the computer to cause the changes to take effect.
8. Access the virtual memory settings to check the properties of the paging file. To do this, follow these steps.

Access the virtual memory settings on a Windows 2000-based computer
a. On the desktop, right-click My Computer, and then click Properties.
b. Click the Advanced tab.
c. Click Performance Options.
d. Click Change.
Access the virtual memory settings on a Windows XP-based or a Windows Server 2003-based computer
a. On the desktop, right-click My Computer, and then click Properties.
b. Click the Advanced tab.
c. Under Performance, click Settings.
d. Click the Advanced tab, and then click Change.
In this example, the initial size of the paging files is set to 3000. You could save disk space by setting the initial size of the extra paging files to 0 so that the space is used only if it is needed. The initial size of the paging file is initialized to the minimum size when the computer starts. If the initial size is 3000, that space is reserved on the disk regardless of whether it is being used.

Note To get a complete memory dump from computers that have 4 GB RAM or more, it is still necessary to use the /maxmem switch in the Boot.ini. One of the page files on the system partition must still be 1 MB larger than the amount of RAM installed in the computer to successfully create a memory dump.


The pagefile may "just be a file"... but Windows treats it as if it were physical RAM installed in the computer. This article should finally prove what I've been trying to explain to you all along.
August 13, 2008 5:29:02 AM

It doesn¨t explain anthing of what you say. I give up.

Just show we are clear. Lets take this one:

Zoron said:
The point I'm trying to make is that 32-bit Windows cannot address more that 4GB of memory total... PAE does get around that physical limit, but the applications also have to support it and there are no consumer applications that do. Now, when you do have 4GB of RAM installed, some address space is of course going to be consumed by hardware. So typically, you have only 3 or 3.5GB of usuable memory left for the OS. It will use this memory + pagefile to equal 4GB total. Without PAE, it will never exceed 4GB of physical usage... because it can't. Pagefile size is irrelevant... no matter how big it is, 32-bit Windows will never make use of more that 4GB of total memory... including both pagefile and physical RAM. Remember, the pagefile is a substitute for physical RAM when there isn't enough available... but again, 32-bit Windows is limited to 4GB.


(You do know the difference between physical and virtual address space?)

If you have installed 4GB RAM, you cannot page anything out? If you have installed 3GB, it makes no sense to have a pagefile larger than 1GB (because 3+1 is 4, and that is the maximum windows can address)? Is that what you are saying here?

Because that is completely false. If you still argue that 32bit Vista cannot possible use for example a 16GB pagefile (like I said, multiple processes can have data paged out to it), then research the subject much more in detail, please. Until then, I don't have anything more to say.
August 13, 2008 5:53:19 PM

Hester7, possibly a short story will help you understand, because it is clear to EVERYBODY but yourself that you do not truly understand the nature of this problem.

This story shall take the analogy of a bar (because I like beer, as noted on an earlier comment). You have two factors, which you seem to have confused, physical memory and virtual memory space. Let’s make beer mugs physical memory, and 32 bit windows is a short barman. In my bar I can fit 4GB of beer mugs on the bar, and a high shelf where I can store as many beer mugs I want to. Since my barman is short he can only reach the mugs on the bar, so he has to POTENTIAL to reach all 4GB of mugs on the bar. He has the potential to reach 4GB of bar height mugs even if I do not fill up my bar with all 4GB of mugs, this is the limit of the virtual memory space (having a short barman). I can put as many mugs on the high shelf as I want, but it won’t help, because my poor barman can’t reach them, 32 bit windows cannot address more than 4GB, it is limited by a memory address size of 32 bits.

Now for RAM and page file. Everybody I know would prefer to drink beer from a proper glass mug instead of a plastic mug, here the glass mugs are system ram and the plastic mugs are page file. The barman manages these, he will give out the glass mugs first to keep his customers happy and the plastic mugs when he runs out of glass mugs, or to people he doesn’t really like. 32 bit windows organises how programs get memory, it will stick everything into ram and only start using the page file when it runs out of lovely fast ram. To a bar patron the mug is still just something for holding beer, be it plastic or glass. Programs don’t get to choose whether they are put into ram or page file, it’s all just memory to them, 32 bit windows decides where they go.

How paging works. If some of the bar patrons who were there late and had plastic mugs suddenly become a famous rock band, the barman will swipe the glass mugs from his worst customers and give them plastic mugs, and gives the band members the glass mugs. When a program that is stored in the page file needs to be run 32 bit windows will swap it with something in RAM so that it can be run faster.

PAE is another short barman, so the first barman can stand on his head to reach the mugs on the high shelf, it works but it’s not as cool as having a tall pretty lady barman. 64 bit is just cooler than 32 bit.
August 13, 2008 9:11:32 PM

This is truly amazing. How you are trying to lecture people, in a degrading manner, when you clearly have no idea what you are talking about. I'm out. For good this time.
August 14, 2008 12:56:11 AM

question...can more than 4 gigs be addressed with windows xp...physical or in page file.
August 14, 2008 1:11:22 AM

Hey hester7,

Can you give link that gives example of 32 bit vista or xp accessing more than 4 gigs even as a page file (or something else)...i am a little confused as i think zoron might be right; but dont really know.
August 14, 2008 10:42:15 AM

I don't know if I can provide you with a link that will explain it to you, black on white in a single sentence. But if you research how memory management works, you'll. know.

Claiming that the paging file claims physical addresses is just nonsense. Anyone that does that, clearly have misunderstood something.

The virtual address space is reused, so that each process has a private user space (defaults to 2GB). Each process can have some of its data paged out. The total amount of paged out data has nothing to do with the 4GB physical addressing limitation.

A hint maybe: in xp and vista, with the pae kernel loaded, each pagefile can be as large as 16TB, otherwise it is limited to 4GB. This is per pagefile. You can have 16 of them. The total pagefile size is the sum of all these together. Ask yourself: how can this be possible, if the pagefile is a part of the physical addressing limitation?
August 14, 2008 1:07:22 PM

hester7, I'll start out by saying that there is a lot I don't know about paging files - you might very well be making a subtle point about the page files that I am simply missing - but I have always understood that the 4 gig limit on a 32 bit MS consumer OS is a virtual limit, not physical (though it of course limits physical also), this is because the 4 gig is what you get when you max out a 32 bit binary number, in other words 2 to the 32 power is 4 gig. In other words the physical limit is BECAUSE of the virtual limit.

The reason this limits using your physical RAM is that the OS only has 4 gig of addresses it can generate and use, that's the 32 bit ceiling, 4 gig, since there are other devices that have addressable memory on them, such as your video card for example, some of these addresses out of the 4 gig total must be reserved to address them, it's not physical ram that is being reserved or used, it's the virtual address space that is limited. The lost RAM just sits there, unused, wasted. If the OS was filling up all your physical RAM there would be no addresses left over for those devices.

You mention that the PAE kernel is loaded . . .it is well known that PAE offered a scheme that got around this 4 gig limit but it is no longer used in any MS CONSUMER OS. I realize PAE is a little more complicated than we realize but it's simply no longer possible. It was tried for a time but because of driver problems it was disabled and remains so on XP and Vista. It is still used on MS server OS. I think we all know that PAE makes going past the 4 gig limit possible but this is no longer relevant. When PAE is used a 32 bit OS can actually use way more than 4 goig of physical RAM http://msdn.microsoft.com/en-us/library/aa366778.aspx

If there is a way for a MS consumer OS (not using PAE) to have many separate page files totaling more than 4 gig (and perhaps there is a way, I don't know) it would seem that it would not be possible for the OS to use these files in any simultaneous way as there would have to be identical addresses in the separate files.

Mark Russinovich spells this out very well here: http://blogs.technet.com/markrussinovich/

Again, you may understand all of this and are making a point more subtle about it, bit if so you may need to spell it out a little more and offer some sort of documentation.
August 14, 2008 1:19:50 PM

Both XP and Vista has a PAE kernel. It is used to support DEP. And with PAE also comes support for large pagefiles. The limitation of 4GB physical address space still exists.

What I say next, I've said a couple of times now. Each process has its very own private user space. On each context switch, this user space portion of the virtual address space is reused. 10 processes together have 10*2GB of user space. Does this mean we address 20GB? No, of couse not. The address space is, as I said, reused.

Each process can have memory paged out. The total pagefile size is not limited by 32 bit addressing. Without PAE (PAE is default these days), each pagefile can be 4GB. And you can define 16 of them. That gives 64GB of total pagefile.

I feel now that I have repeated my self more times than I like.
August 14, 2008 1:33:32 PM

NP. I'll look into it more deeply.

I'm not here to argue this point because there is too much I don't know about it. What's confusing me is PAE - as a means of getting past the 'can't use my RAM' problem I know it is no longer used on MS consumer OS versions - but it sounds like you are agreeing with that but saying that PAE is still there affecting the virtual limit. Is this correct?
August 14, 2008 7:35:40 PM

notherdude, this article explains PAE and MS operating systems quite nicely.

PAE: "PAE doesn't do anything to the virtual memory limit. Pointers are still 32 bits, so a process can only access 4 GB of address space at a time. However, using PAE, two or more processes could each access a different 4 GB of physical memory."

hester7: yes, you can have multiple processes addressing multiple portions of physical memory with PAE.

But it's not in Vista 32: "XP SP2 introduced a change such that only the bottom 32 bits of physical memory will ever be used, even if that means some memory will not be used. (This is also the case with 32-bit editions of Vista.)'

I must admit I think I fail when it comes to including paging file space in the 32 bit virtual memory space to be fair.

Hester7, just checking what you mean by 4GB physical addressing limitation, physical RAM limitation by CPU pins and motherboard bus, not the 4GB limitation by 32 bit virtual addressing space? PAE dose is not used to support DEP, it is often the cause for DEP errors though, please read this article.
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