Recommendation for windows 2008 and R2 for page file size.

We are creating a standard build for windows 2008 and windows 2008R2 for remote offices who have different servers and application roles.

I know there are many arguments to what size should be and that you should use permon for further optimization for the size but we are trying to come up with a standard build doc and further optimizations can be done upon request.

Here is the scope:

1) Page files initial size will be 1.5 times RAM installed.
2) Page file max will be 2 time RAM installed
3) If RAM is more than 50GB then Page file MAX will be 50GB or 100GB (not sure what is best).

Some of these servers are sql database server, some are host small IIS sites, and so forth..

So the questions is,
 Should we have the min and max to be the same size to avoid fragmentation of the file?
 Do you think this is a good practice for setting page file size?
 If a server has massive memory (64GB or more) what do you think would a good argument for size?
 Should we consider different page file size for VMs as opposed to physical?
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onlinerackAsked:
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pschakravarthiCommented:

Should we have the min and max to be the same size to avoid fragmentation of the file?  Do you think this is a good practice for setting page file size?

Ans :

To have Windows choose the best paging file size, click System managed size. The recommended minimum size is equivalent to 1.5 times the amount of RAM on your system, and 3 times that figure for the maximum size. Example, if you have 256 MB of RAM, the minimum size would be 384, the maximum size would be 1152.

For best performance, do not set the initial size to less than the minimum recommended size under Total paging file size for all drives. The recommended size is equivalent to 1.5 times the amount of RAM on your system. Usually, you should leave the paging file at its recommended size, although you might increase its size if you routinely use programs that require a lot of memory.

To delete a paging file, set both initial size and maximum size to zero, or click No paging file. Microsoft strongly recommends that you do not disable or delete the paging file.

To determine your preferred Pagefile size you should monitor your system and see how much RAM and virtual memory it uses. Do a baseline monitoring for a week or so (you can skip the baseline or shorten its duration if you know exactly how much Pagefile you need) and see what was the largest amount of memory your system ever used. If you see it never gets close to the maximum amount of RAM you have installed – don't worry. Your Pagefile is virtually left untouched (not exactly correct, because the system uses the Pagefile for some internal operations and it should keep it at around 5%-10% usage on normal systems). If, on the other hand, you see your system uses more memory than it physically has, this means it uses some Pagefile.


 If a server has massive memory (64GB or more) what do you think would a good argument for size?

Ans :
It's all depend upon the application usage.  Below URL will help you better in analyzing page file utilization.

http://support.microsoft.com/kb/889654

Should we consider different page file size for VMs as opposed to physical?

Ans : No advantage with this.  Try to keep Pagefile on non system drive.  It would be better if you can keep the system drive and page file drive on different LUNs
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Darius GhassemCommented:
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rizla7Commented:
i dont know of any specific guidelines. i think the general ones you are thinking of are fine.

some things to keep in mind:

if you place the page file on a separate partition you dont have to worry about fragmentation.

if you let windows manage the swap size or set a minimum different than the maximum, you might encounter brief periods of unresponsiveness as windows extends/truncates the swap file. this may be undesirable on a server. although windows is usually pretty good at managing it and i've only personally experienced 2 such instances in a very long time.

the drive on which the NTDS database is stored will have 'write cache' disabled. writes to that drive will be 50-70% slower. do not store the swap file on the same drive.

the general rule is 1.5 times your ram, up to twice the amount for some application but not more. you can set at 1.5 and monitor swap file usage in your environment and tweak.
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Alex GalbraithSolutions ArchitectCommented:
"Should we have the min and max to be the same size to avoid fragmentation of the file?"

Most definitly yes, and if you can put this one a seperate spindle, you will see perforemance gain too. Ive never needed to increase it beyond 1.5x for both min and max when running SQL server.
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onlinerackAuthor Commented:
@rizla7  can you please elaborate: if you place the page file on a separate partition you dont have to worry about fragmentation.

So you guys suggest the size for the initial and max to be the same size?
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Darius GhassemCommented:
No, I would have a min and max that is higher.
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rizla7Commented:
well, if the pagefile is on it's own partition then windows can extend the size and the space right after it on the drive is guaranteed to be free, so no fragmentation. or the fragmentation would be VERY minimal at most.
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onlinerackAuthor Commented:
the page file will be on the same partition as the system (vms) so fragmentation would be an issue right? some machines have 2GB RAM and others will have 12GB of RAM.
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rizla7Commented:
that will be more than an issue hehe.

#1. each VM should have it's own separate HDD. if that is not possible, at most 2 vms on one hdd.

#2. if that machine is running a DC, put the ntds db on a separate disk or it will kill your write speed by disabling write cache.

#3. if 2 swap files and 2 OS boot partitions are on one disk, that disk won't last very long :\
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onlinerackAuthor Commented:
yea, we have a $400k SAN in place 128 hard drives :)

but trying to figure out a good standard build for the swap file... we got everything else.
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rizla7Commented:
lol. fantasizing a bit i see... well, i think you got everything you need. there are tools to defrag the page file but i don't think that's something you want to be doing on a server, but if you must, you must. the page file should be on a separate partition for performance reasons. technically it should be on a separate disk. you want to prevent windows from resizing the paging file, etc etc.. i dont think anything has changed with respect to the paging file in the last 10 years ;p

you must use perfmon to monitor page file performance in your environment. there really is no other way, but the general guidelines work for most cases, and the improvement you can get by tweaking is negligable.
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onlinerackAuthor Commented:
:) this is the SAN that is in place
http://h10010.www1.hp.com/wwpc/us/en/sm/WF06a/12169-304616-304648-304648-304648-3900918.html

My question is really this, we are looking for servers that will not have a second drive, they will have one C: drive, so what can we do with the swap file, make it initial size different from max size or keep it the same?  some of these machines will have 2GB of memory and others will have upto 12GB of RAM.

The main servers we support will be and have been optimized via permon and commit peak counters and closely monitored. but I am looking at the other VMs that we do not necessarily support, we just build them and pass them off to the application teams.


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LMiller7Commented:
Unless you have a specific reason to do otherwise, leave them all on system managed. Unless you take the time to analyze requirements on a case by case basis you aren't going to do much better than that.

Forget pagefile fragmentation. Only in very rare cases will it be a serious issue in performance. In most cases it will not be an issue at all.

Putting the pagefile on a separate physical drive may improve performance. But note that it must be a separate physical drive, not just a separate partition. But if you have adequate RAM it probably won't be worth bothering with.

In most cases pagefile performance is not that important to overall system performance. Attempts to optimize it are rarely worth the effort.
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rizla7Commented:
if it's one drive, i hope it isnt a domain controller.. that will be uber slow.

in that case i would put the swap on the FIRST partition on the drive. make sure it has enough room. i would give it 4-5 times your ram to deal with future enlargements, etc..

the first partition will be the fastest for sequential reads, which the pagefile DOES do, despite contradictions out there. it also does alot of random access reads, those wont improve that much on the first partition, but they will slightly.

leave the system to automanage the swap if you want, like i said it doesnt resize that often. if you find resizing is locking i/o on the server too often, you can always set the size.
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rizla7Commented:
if you have 12gb of ram 4-5 times the size might not be possible depending on your drive, you may want to be a bit more conservative then. 2-3 times the size
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rizla7Commented:
sorry, i guess i should mention, you dont wanna push you boot partition too far towards the end of the drive because that will slow it down, so be conservative. do not make that first partition more than say... 5% or your total drive capacity.

generally, anything you want to run faster, you want at the outer edge of your disk. this includes windows system files, databases, etc..
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onlinerackAuthor Commented:
OK thank you all for your help. I have a final question and I will accept your answers. :)

If we put the pagefile on a different partition (which I plan to do when possible), what would you do on the system partition for kernel dump, would you risk not getting a kernel dump since you do not have the pagefile on the same system partition?

I think having multiple page files on different drives is not a good practice, would you guys not agree?

if a physical server has a mirrored OS partition, and another drive on the SAN, would you put the page file on the SAN or would you keep it on the OS partition since you will likely have less latency?
Just picking your brain on this as I know many people would love to see another view from other professionals.

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rizla7Commented:
what would you need a kernel dump for? you only need it for debugging. if it's bluescreening, create a new swap on the system partition, wait for dump, rinse repeat.

in the unlikely case it dumps and wont boot, try safe mode, adsr, recovery, restore, reimage, rebuild.. wtfever. its quicker than debugging some drivers ;p
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rizla7Commented:
LKG - last known good. be careful with this one though. also you can manage shadow copies and system restore points from recovery console i believe.
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rizla7Commented:
this is like 2 question now :O
i demand double
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LMiller7Commented:
The general rule for pagefile location is on the most used partition of the least used hard disk. For a single disk that means the system partition. Putting it on a separate partition of the system drive is almost always a bad idea.

But as I said before, all this talk of pagefile location and size, etc, is usually much adu about very little. You have more important things to occupy your time with.
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onlinerackAuthor Commented:
So would you put the page file on a system drive which is a local RAID1 disk or on a SAN attached seperate drive (which some would say has a latency)?
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Alex GalbraithSolutions ArchitectCommented:
Putting it on locally attached storage is fine. I generally split it 64mb on the system drive and the rest on the secondary drive, then set your windows dump file to a minidump (full dumps are pretty useless unless you work for MS anyway, and a minidump can be analysed to tell you what caused a crash). This method has always proved successful for me.
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rizla7Commented:
if you have 2 drives you can split it, but he specifically said 1 drive.
splitting it between 2 partitions IS definately a bad idea.

and putting it on the leading partition is not a bad idea like lmiller says.
even if you do put the swap on the same partition as system/most used you still don't avoided having to seek to the swap file.

also. incorrect that managing the swap file does not yield performance.
for example, if you have multiple disks to split the pagefile to, windows will try to write to the least used disk at any one time.

there are lots of defrag tools which specifically allow you to place files at the beginning of a partition, one of them usually being the swap file. if you could put it on a separate partition (the first partition) of the drive, assuming it is small enough so it doesnt push your other data further onto the center of the plate.

i still don't see why you need a minidump... there's safe mode, LKG, etc etc etc etc etc.. im done.

putting it on a disk with something other than 4k clusters.
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Alex GalbraithSolutions ArchitectCommented:
You need a minidump for unexpected reboots so you can diagnose what the offending executable was that knocked over your OS. You should never have all dumps disabled completely. Safe mode and LKG have nothing to do with the need for dumps.
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onlinerackAuthor Commented:
Thanks guys, sorry for taking too long. It was a good topic and covered quite a bit. I did learn one thing, there is a common answer but not a solid one when it comes to pagefile which I expected but wanted to see first hand.
keep up the good work.
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rizla7Commented:
executable? you mean like the ones that are not loaded in safe mode?

a driver maybe? like the ones not loaded in safe mode?

a system driver? like the ones that can be recovered with recovery, sfc, restore?

i don't think i understand..
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rizla7Commented:
almost never does a system bluescreen in safemode unless its a system driver which can be recovered.

if its not a system drivers, boot to safe, create system part swap, reboot...
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Alex GalbraithSolutions ArchitectCommented:
Im not talking about recovery - im talking about root cause analysis, something commonly carried out in large, ITIL managed environments. I repeat, safe mode and LKG have nothing to do with the need for dumps.
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rizla7Commented:
root cause analysis of a system driver?
i think that is cost prohibitive for most companies.
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Alex GalbraithSolutions ArchitectCommented:
Are you getting confused between drives and drivers?
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