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Virtual Memory

Hi,
  I like to know how much I need to allocate to paging file for my Windows 2008 Server Std. 64-bit with 8GB of RAM / 300GB SAS HD (will be set up as Terminal Server)

  The default installation allocated 8,453MB.
  The Recommended is 12,229MB according to the System Properties/Performance Options/Virtual Memory window.
  Should I change it to 12,229MB or not?
  Will I see the performance increase if I change it to 12,229MB?
 
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sglee
Asked:
sglee
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1 Solution
 
DavidCommented:
if you don't have enough then the system may crash (i can't say will crash, but that is possibility)

just let the system manage it.  the os will allocate whatit needs, when it needs it.  if it needs more then you allow, it will let you know.

the amount you need is a function of what you are running mostly. it has nothing to do with how much total disk space (unless you don't have enough free space)
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TSSTJeffCommented:
In my experience I have found there is a performance increase if you manually set the maximum and minimum to at least 4096.  depending on harddrive space and physical memory or less may be appropriate.  But, by setting the amount to a fixed size the operating system dosent use any resources in resizing the paging file.  it also means that if you get low on space the reserved space is protected and will continue to allow the server to run even if drive space is all used.
Microsoft has provided a guideline for this
http://support.microsoft.com/kb/889654
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oneitnzCommented:
Just following on from TSSTJeff's comments always bear in mind that if the Paging file isn't set to a Fixed Size and the disk is quite full and even sometimes if its not full you may find that when the Page File automatically increases in size it will get fragmented which is not good. You can defragment it but its just easier to not let it get fragmented.

Also the amount of Page File size really depends on how much memory your users will need, if this terminal server will have lots of users on it or they will be running memory hungry programs you'll probably need to set this quite high.

Microsoft Recommends a Page File Size of 1.5x the size of memory hence why the recommended your seeing is 12GB. This was true back when servers would only contain 1 or 2 GB of ram but nowadays we're getting servers with 8GB and higher and there is less emphasis on paging operations.

One other thing to note is that if you have a BSOD on the server it will try to write everything in Memory to the page file so if it is less than the Total Physical Memory the dump wont be created fully.

My personal opinion is to set it to a fixed size of the amount of memory you have and then keep an eye on the memory usage that your users are taking up. Then decide if too much is being paged and you still have plenty of Ram decrease the Page File Size. On the other hand if the memory is all used up and the page file is too then you probably need more Ram.

Regards
Brett Smith
One IT - IT Specialists
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sgleeAuthor Commented:
To all,
 
  So let me gather what I heard.
  If I don't have to EVER worry about running out of hard drive space (I won't because it has 300GB HD / 8GB RAM and there are about 10 users opeing WORD/EXCEL/ACCESS files from File Server), I can set it to Fxied/Manual 12GB that is recommended by O.S.? (Min. 12GB, Max 12GB so that it allocates the maximum size to produce maximum performance and to handle BSOD situation shoud it occur?)
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oneitnzCommented:
That is perfect sqlee.
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DavidCommented:
"I won't because it has 300GB HD / 8GB RAM and there are about 10 users opeing WORD/EXCEL/ACCESS files from File Server"

Right, and 640KB of RAM should be enough for anybody ;)
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sgleeAuthor Commented:
To oneitnz,
 
"Microsoft Recommends a Page File Size of 1.5x the size of memory hence why the recommended your seeing is 12GB. This was true back when servers would only contain 1 or 2 GB of ram but nowadays we're getting servers with 8GB and higher and there is less emphasis on paging operations"

Let me understand above. Are you saying that when PC/Server comes with 512GB-2GB, we need to take advantage of paging operation by allocating up to 1.5x of RAM because lack of memory. However when you have more than enough memory on a computer with 8GB (in this case or I recently ordered a new server for SBS2011 with 32GB of RMA), the paging function is not critical?
If all the pieces of information can be stored in the memory, why do we need to even bother setting up the paging file? I will never use memory dump in case of BSOD because I can't make sense out of it.

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oneitnzCommented:
Hi sqlee
SBS 2011 is an entirely different story, Firstly it contains Active Directory which according to this Microsoft Support Article: http://support.microsoft.com/kb/889654 requires a paging file. Read This:

Windows Domain Controllers and DFS Replication, Certificate and ADAM/LDS Servers are not supported without a configured pagefile. Because the algorithm the LSASS database cache depends on the "transition pages repurposed/second" perfmon counter, a pagefile is required to make sure that the database cache is capable to release memory if memory is requested by other services or applications.

Now in saying that you may still have more than enough memory in your system that this scenario may never happen, but SBS 2011 also contains Exchange 2010 and if you see this Technet Article: http://technet.microsoft.com/en-us/library/aa996719(EXCHG.140).aspx (note: Expand Hardware) you'll see that it says:

The page file size minimum and maximum MUST be set to physical RAM plus 10  MB

When you have a server that is just used for File Based Activities (ie File Server, Terminal Server, Web Server) and you have plenty of Physical Ram then you'll most likely not require a Page File. However when you have Database Applications (SQL or Exchange) then these applications try to load as much information into memory as possible and only release memory if something requires it. Additionally these programs use Performance Counters like Pages/Sec to monitor if other applications are requiring the use of more memory so if you were to have a small Page File then your likely to see more read write access to the page file and Exchange will then think that it needs to release memory and will then cause more Paging.

So in your situation with the SBS Server I would set the Page File Size to Physical Ram + 10MB, however on the Terminal Server its really a matter of how much memory each user will use. I would set it to No Page File and monitor free memory if it drops to low when everyone is using it then just fix it to Physical Ram +10MB also.

Regards
Brett Smith
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DavidCommented:
.. or just let SBS manage the size.  You said earlier, that you had plenty of disk space, so I don't see any upside to not letting the O/S manage it automatically.
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oneitnzCommented:
Because Dlethe it is always advisable to set the Page File to Manual so that its Size is fixed so that you don't run into problems with the page file automatically increasing and then becoming Fragmented.

Fragmented Page Files are the worst and if possible you want to ensure that your Page File is at the Start of your Hard Disk for best Access Time. Use something like MyDefrag to get an idea of where your Page File is currently sitting (Bottom of the Display is the Start of the Hard Disk in MyDefrag Gui) and how many Fragments its currently in.

Regards
Brett
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sgleeAuthor Commented:
Thanks guys for your expertise on this matter and I appreciate all of your advise.

Due to the possibility of Fragmented Page Files with "WIndows managed Page Files", I think I will go with fixed paging file size approach.

Thanks you again.
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